Processing-in-memory (pim) system including multiplying-and-accumulating (mac) circuit

ABSTRACT

A multiplying-and-accumulating (MAC) circuit includes a multiplying circuit and an adding circuit. The multiplying circuit includes a first multiplier and a second multiplier, and each of the first multiplier and the second multiplier performs a multiplying calculation for first input data with N bits and second input data with M bits to output multiplication result data with (N+M) bits (where, “N” and “M” are natural numbers which are equal to or greater than one). The adding circuit includes an adder which performs an adding calculation for the multiplication result data of the first multiplier and the multiplication result data of the second multiplier to output addition result data with (N+M) bits.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No. 17/027,276, filed Sep. 21, 2020, which claims the priority of provisional application No. 62/958,226, filed on Jan. 7, 2020, and Korean Application No. 10-2020-0006903, filed on Jan. 17, 2020, which are incorporated herein by reference in their entirety. This application claims the provisional application No. 62/959,604, filed on Jan. 10, 2020, which is incorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

Various embodiments of the present disclosure relate to processing-in-memory (PIM) systems and, more particularly, to PIM systems including a MAC circuit.

2. Related Art

Recently, interest in artificial intelligence (AI) has been increasing not only in the information technology industry but also in the financial and medical industries. Accordingly, in various fields, artificial intelligence, more precisely, the introduction of deep learning, is considered and prototyped. In general, techniques for effectively learning deep neural networks (DNNs) or deep networks with increased layers as compared with general neural networks to utilize the deep neural networks (DNNs) or the deep networks in pattern recognition or inference are commonly referred to as deep learning.

One cause of this widespread interest may be the improved performance of processors performing arithmetic operations. To improve the performance of artificial intelligence, it may be necessary to increase the number of layers constituting a neural network in the artificial intelligence to educate the artificial intelligence. This trend has continued in recent years, which has led to an exponential increase in the amount of computation required for the hardware that actually does the computation. Moreover, if the artificial intelligence employs a general hardware system including memory and a processor which are separated from each other, the performance of the artificial intelligence may be degraded due to limitation of the amount of data communication between the memory and the processor. In order to solve this problem, a PIM device in which a processor and memory are integrated in one semiconductor chip has been used as a neural network computing device. Because the PIM device directly performs arithmetic operations internally, data processing speed in the neural network may be improved.

SUMMARY

According to an embodiment, a multiplying-and-accumulating (MAC) circuit includes a multiplying circuit and an adding circuit. The multiplying circuit includes a first multiplier and a second multiplier, and each of the first multiplier and the second multiplier performs a multiplying calculation for first input data with N bits and second input data with M bits to output multiplication result data with (N+M) bits (where, “N” and “M” are natural numbers which are equal to or greater than one). The adding circuit includes an adder which performs an adding calculation for the multiplication result data of the first multiplier and the multiplication result data of the second multiplier to output addition result data with (N+M) bits.

According to another embodiment, a multiplying-and-accumulating (MAC) circuit includes a multiplying circuit and an adding circuit. The multiplying circuit includes a plurality of multipliers, and each of the plurality of multipliers performs a multiplying calculation for first input data with N bits and second input data with M bits to output multiplication result data with (N+M) bits (where, “N” and “M” are natural numbers which are equal to or greater than one). The adding circuit is configured to receive output data of the multiplying circuit. The adding circuit has a tree structure including a plurality of stages, each of which has one or more adders. Each of the adders is configured to receive first data and second data to generate output data with the same number of bits as the first data or the second data.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain features of the disclosed technology are illustrated in various embodiments with reference to the attached drawings.

FIG. 1 is a block diagram illustrating a PIM system according to an embodiment of the present disclosure.

FIG. 2 is a block diagram illustrating a PIM system according to a first embodiment of the present disclosure.

FIG. 3 illustrates MAC commands that are output from a MAC command generator of a PIM controller included in a PIM system according to a first embodiment of the present disclosure.

FIG. 4 is a block diagram illustrating an example of a configuration of a MAC operator of a PIM device included in a PIM system according to a first embodiment of the present disclosure.

FIG. 5 illustrates an example of a MAC arithmetic operation performed in a PIM system according to a first embodiment of the present disclosure.

FIG. 6 is a flowchart illustrating processes of the MAC arithmetic operation illustrated in FIG. 5 in a PIM system according to a first embodiment of the present disclosure.

FIGS. 7 to 13 are block diagrams illustrating processes of the MAC arithmetic operation illustrated in FIG. 5 in a PIM system according to a first embodiment of the present disclosure.

FIG. 14 illustrates another example of a MAC arithmetic operation performed in a PIM system according to a first embodiment of the present disclosure.

FIG. 15 is a flowchart illustrating processes of the MAC arithmetic operation illustrated in FIG. 14 in a PIM system according to a first embodiment of the present disclosure.

FIG. 16 illustrates an example of a configuration of a MAC operator for performing the MAC arithmetic operation of FIG. 14 in a PIM system according to a first embodiment of the present disclosure.

FIG. 17 illustrates yet another example of a MAC arithmetic operation performed in a PIM system according to a first embodiment of the present disclosure.

FIG. 18 is a flowchart illustrating processes of the MAC arithmetic operation illustrated in FIG. 17 in a PIM system according to a first embodiment of the present disclosure.

FIG. 19 illustrates an example of a configuration of a MAC operator for performing the MAC arithmetic operation of FIG. 17 in a PIM system according to a first embodiment of the present disclosure.

FIG. 20 is a block diagram illustrating a PIM system according to a second embodiment of the present disclosure.

FIG. 21 illustrates MAC commands that are output from a MAC command generator of a PIM controller included in a PIM system according to a second embodiment of the present disclosure.

FIG. 22 is a flowchart illustrating processes of the MAC arithmetic operation illustrated in FIG. 5 in a PIM system according to a second embodiment of the present disclosure.

FIGS. 23 to 26 are block diagrams illustrating processes of the MAC arithmetic operation illustrated in FIG. 5 in a PIM system according to a second embodiment of the present disclosure.

FIG. 27 is a flowchart illustrating processes of the MAC arithmetic operation illustrated in FIG. 14 in a PIM system according to a second embodiment of the present disclosure.

FIG. 28 is a flowchart illustrating processes of the MAC arithmetic operation illustrated in FIG. 17 in a PIM system according to a second embodiment of the present disclosure.

FIG. 29 is a block diagram illustrating a PIM system according to yet another embodiment of the present disclosure.

FIG. 30 is a block diagram illustrating a PIM system according to still another embodiment of the present disclosure.

FIG. 31 is a block diagram illustrating a MAC circuit according to an embodiment of the present disclosure.

FIG. 32 is a block diagram illustrating a configuration of an adder of an adding circuit including the MAC circuit illustrated in FIG. 31.

FIG. 33 is a block diagram illustrating a MAC circuit according to another embodiment of the present disclosure and illustrating the number of bits included in data according to an operation of the MAC circuit.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description of embodiments, it will be understood that the terms “first” and “second” are intended to identify elements, but not used to define a particular number or sequence of elements. In addition, when an element is referred to as being located “on,” “over,” “above,” “under,” or “beneath” another element, it is intended to mean a relative positional relationship, but not used to limit certain cases in which the element directly contacts the other element, or at least one intervening element is present therebetween. Accordingly, the terms such as “on,” “over,” “above,” “under,” “beneath,” “below,” and the like that are used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the present disclosure. Further, when an element is referred to as being “connected” or “coupled” to another element, the element may be electrically or mechanically connected or coupled to the other element directly, or may be electrically or mechanically connected or coupled to the other element indirectly with one or more additional elements therebetween.

Various embodiments are directed to PIM systems and methods of operating the PIM systems.

FIG. 1 is a block diagram illustrating a PIM system according to an embodiment of the present disclosure. As illustrated in FIG. 1, the PIM system 1 may include a PIM device 10 and a PIM controller 20. The PIM device 10 may include a data storage region 11, an arithmetic circuit 12, an interface (I/F) 13-1, and a data (DQ) input/output (I/O) pad 13-2. The data storage region 11 may include a first storage region and a second storage region. In an embodiment, the first storage region and the second storage region may be a first memory bank and a second memory bank, respectively. In another embodiment, the first data storage region and the second storage region may be a memory bank and buffer memory, respectively. The data storage region 11 may include a volatile memory element or a non-volatile memory element. For an embodiment, the data storage region 11 may include both a volatile memory element and a non-volatile memory element.

The arithmetic circuit 12 may perform an arithmetic operation on the data transferred from the data storage region 11. In an embodiment, the arithmetic circuit 12 may include a multiplying-and-accumulating (MAC) operator. The MAC operator may perform a multiplying calculation on the data transferred from the data storage region 11 and perform an accumulating calculation on the multiplication result data. After MAC operations, the MAC operator may output MAC result data. The MAC result data may be stored in the data storage region 11 or output from the PIM device 10 through the data I/O pad 13-2.

The interface 13-1 of the PIM device 10 may receive a command signal CMD and address signal ADDR from the PIM controller 20. The interface 13-1 may output the command signal CMD to the data storage region 11 or the arithmetic circuit 12 in the PIM device 10. The interface 13-1 may output the address signal ADDR to the data storage region 11 in the PIM device 10. The data I/O pad 13-2 of the PIM device 10 may function as a data communication terminal between a device external to the PIM device 10, for example the PIM controller 20, and the data storage region 11 included in the PIM device 10. The external device to the PIM device 10 may correspond to the PIM controller 20 of the PIM system 1 or a host located outside the PIM system 1. Accordingly, data that is output from the host or the PIM controller 20 may be input into the PIM device 10 through the data I/O pad 13-2.

The PIM controller 20 may control operations of the PIM device 10. In an embodiment, the PIM controller 20 may control the PIM device 10 such that the PIM device 10 operates in a memory mode or an arithmetic mode. In the event that the PIM controller 20 controls the PIM device 10 such that the PIM device 10 operates in the memory mode, the PIM device 10 may perform a data read operation or a data write operation for the data storage region 11. In the event that the PIM controller 20 controls the PIM device 10 such that the PIM device 10 operates in the arithmetic mode, the arithmetic circuit 12 of the PIM device 10 may receive first data and second data from the data storage region 11 to perform an arithmetic operation. In the event that the PIM controller 20 controls the PIM device 10 such that the PIM device 10 operates in the arithmetic mode, the PIM device 10 may also perform the data read operation and the data write operation for the data storage region 11 to execute the arithmetic operation. The arithmetic operation may be a deterministic arithmetic operation performed during a predetermined fixed time. The word “predetermined” as used herein with respect to a parameter, such as a predetermined fixed time or time period, means that a value for the parameter is determined prior to the parameter being used in a process or algorithm. For some embodiments, the value for the parameter is determined before the process or algorithm begins. In other embodiments, the value for the parameter is determined during the process or algorithm but before the parameter is used in the process or algorithm.

The PIM controller 20 may be configured to include command queue logic 21, a scheduler 22, a command (CMD) generator 23, and an address (ADDR) generator 25. The command queue logic 21 may receive a request REQ from an external device (e.g., a host of the PIM system 1) and store the command queue corresponding to the request REQ in the command queue logic 21. The command queue logic 21 may transmit information on a storage status of the command queue to the scheduler 22 whenever the command queue logic 21 stores the command queue. The command queue stored in the command queue logic 21 may be transmitted to the command generator 23 according to a sequence determined by the scheduler 22. The command queue logic 21, and also the command queue logic 210 of FIGS. 2 and 20, may be implemented as hardware, software, or a combination of hardware and software. For example, the command queue logic 21 and/or 210 may be a command queue logic circuit operating in accordance with an algorithm and/or a processor executing command queue logic code.

The scheduler 22 may adjust a sequence of the command queue when the command queue stored in the command queue logic 21 is output from the command queue logic 21. In order to adjust the output sequence of the command queue stored in the command queue logic 21, the scheduler 22 may analyze the information on the storage status of the command queue provided by the command queue logic 21 and may readjust a process sequence of the command queue so that the command queue is processed according to a proper sequence.

The command generator 23 may receive the command queue related to the memory mode of the PIM device 10 and the MAC mode of the PIM device 10 from the command queue logic 21. The command generator 23 may decode the command queue to generate and output the command signal CMD. The command signal CMD may include a memory command for the memory mode or an arithmetic command for the arithmetic mode. The command signal CMD that is output from the command generator 23 may be transmitted to the PIM device 10.

The command generator 23 may be configured to generate and transmit the memory command to the PIM device 10 in the memory mode. The command generator 23 may be configured to generate and transmit a plurality of arithmetic commands to the PIM device 10 in the arithmetic mode. In one example, the command generator 23 may be configured to generate and output first to fifth arithmetic commands with predetermined time intervals in the arithmetic mode. The first arithmetic command may be a control signal for reading the first data out of the data storage region 11. The second arithmetic command may be a control signal for reading the second data out of the data storage region 11. The third arithmetic command may be a control signal for latching the first data in the arithmetic circuit 12. The fourth arithmetic command may be a control signal for latching the second data in the arithmetic circuit 12. And the fifth MAC command may be a control signal for latching arithmetic result data of the arithmetic circuit 12.

The address generator 25 may receive address information from the command queue logic 21 and generate the address signal ADDR for accessing a region in the data storage region 11. In an embodiment, the address signal ADDR may include a bank address, a row address, and a column address. The address signal ADDR that is output from the address generator 25 may be input to the data storage region 11 through the interface (I/F) 13-1.

FIG. 2 is a block diagram illustrating a PIM system 1-1 according to a first embodiment of the present disclosure. As illustrated in FIG. 2, the PIM system 1-1 may include a PIM device 100 and a PIM controller 200. The PIM device 100 may include a first memory bank (BANK0) 111, a second memory bank (BANK1) 112, a MAC operator 120, an interface (I/F) 131, and a data input/output (I/O) pad 132. For an embodiment, the MAC operator 120 represents a MAC operator circuit. The first memory bank (BANK0) 111, the second memory bank (BANK1) 112, and the MAC operator 120 included in the PIM device 100 may constitute one MAC unit. In another embodiment, the PIM device 100 may include a plurality of MAC units. The first memory bank (BANK0) 111 and the second memory bank (BANK1) 112 may represent a memory region for storing data, for example, a DRAM device. Each of the first memory bank (BANK0) 111 and the second memory bank (BANK1) 112 may be a component unit which is independently activated and may be configured to have the same data bus width as data I/O lines in the PIM device 100. In an embodiment, the first and second memory banks 111 and 112 may operate through interleaving such that an active operation of the first and second memory banks 111 and 112 is performed in parallel while another memory bank is selected. Each of the first and second memory banks 111 and 112 may include at least one cell array which includes memory unit cells located at cross points of a plurality of rows and a plurality of columns.

Although not shown in the drawings, a core circuit may be disposed adjacent to the first and second memory banks 111 and 112. The core circuit may include X-decoders XDECs and Y-decoders/IO circuits YDEC/IOs. An X-decoder XDEC may also be referred to as a word line decoder or a row decoder. The X-decoder XDEC may receive a row address ADD_R from the PIM controller 200 and may decode the row address ADD_R to select and enable one of the rows (i.e., word lines) coupled to the selected memory bank. Each of the Y-decoders/IO circuits YDEC/IOs may include a Y-decoder YDEC and an I/O circuit JO. The Y-decoder YDEC may also be referred to as a bit line decoder or a column decoder. The Y-decoder YDEC may receive a column address ADDR_C from the PIM controller 200 and may decode the column address ADDR_C to select and enable at least one of the columns (i.e., bit lines) coupled to the selected memory bank. Each of the I/O circuits may include an I/O sense amplifier for sensing and amplifying a level of a read datum that is output from the corresponding memory bank during a read operation for the first and second memory banks 111 and 112. In addition, the I/O circuit may include a write driver for driving a write datum during a write operation for the first and second memory banks 111 and 112.

The interface 131 of the PIM device 100 may receive a memory command signal M_CMD, a MAC command signals MAC_CMDs, a bank selection signal BS, and the row/column addresses ADDR_R/ADDR_C signal from the PIM controller 200. The interface 131 may output the memory command signal M_CMD, together with the bank selection signal BS and the row/column addresses ADDR_R/ADDR_C signal, to the first memory bank 111 or the second memory bank 112. The interface 131 may output the MAC command signals MAC_CMDs to the first memory bank 111, the second memory bank 112, and the MAC operator 120. In such a case, the interface 131 may output the bank selection signal BS and the row/column addresses ADDR_R/ADDR_C signal to both of the first memory bank 111 and the second memory bank 112. The data I/O pad 132 of the PIM device 100 may function as a data communication terminal between a device external to the PIM device 100 and the MAC unit (which includes the first and second memory banks 111 and 112 and the MAC operator 120) included in the PIM device 100. The external device to the PIM device 100 may correspond to the PIM controller 200 of the PIM system 1-1 or a host located outside the PIM system 1-1. Accordingly, data that is output from the host or the PIM controller 200 may be input into the PIM device 100 through the data I/O pad 132.

The PIM controller 200 may control operations of the PIM device 100. In an embodiment, the PIM controller 200 may control the PIM device 100 such that the PIM device 100 operates in a memory mode or a MAC mode. In the event that the PIM controller 200 controls the PIM device 100 such that the PIM device 100 operates in the memory mode, the PIM device 100 may perform a data read operation or a data write operation for the first memory bank 111 and the second memory bank 112. In the event that the PIM controller 200 controls the PIM device 100 such that the PIM device 100 operates in the MAC mode, the PIM device 100 may perform a MAC arithmetic operation for the MAC operator 120. In the event that the PIM controller 200 controls the PIM device 100 such that the PIM device 100 operates in the MAC mode, the PIM device 100 may also perform the data read operation and the data write operation for the first and second memory banks 111 and 112 to execute the MAC arithmetic operation.

The PIM controller 200 may be configured to include command queue logic 210, a scheduler 220, a memory command generator 230, a MAC command generator 240, and an address generator 250. The command queue logic 210 may receive a request REQ from an external device (e.g., a host of the PIM system 1-1) and store a command queue corresponding to the request REQ in the command queue logic 210. The command queue logic 210 may transmit information on a storage status of the command queue to the scheduler 220 whenever the command queue logic 210 stores the command queue. The command queue stored in the command queue logic 210 may be transmitted to the memory command generator 230 or the MAC command generator 240 according to a sequence determined by the scheduler 220. When the command queue that is output from the command queue logic 210 includes command information requesting an operation in the memory mode of the PIM device 100, the command queue logic 210 may transmit the command queue to the memory command generator 230. On the other hand, when the command queue that is output from the command queue logic 210 is command information requesting an operation in the MAC mode of the PIM device 100, the command queue logic 210 may transmit the command queue to the MAC command generator 240. Information on whether the command queue relates to the memory mode or the MAC mode may be provided by the scheduler 220.

The scheduler 220 may adjust a timing of the command queue when the command queue stored in the command queue logic 210 is output from the command queue logic 210. In order to adjust the output timing of the command queue stored in the command queue logic 210, the scheduler 220 may analyze the information on the storage status of the command queue provided by the command queue logic 210 and may readjust a process sequence of the command queue such that the command queue is processed according to a proper sequence. The scheduler 220 may output and transmit to the command queue logic 210 information on whether the command queue that is output from the command queue logic 210 relates to the memory mode of the PIM device 100 or relates to the MAC mode of the PIM device 100. In order to obtain the information on whether the command queue that is output from the command queue logic 210 relates to the memory mode or the MAC mode, the scheduler 220 may include a mode selector 221. The mode selector 221 may generate a mode selection signal including information on whether the command queue stored in the command queue logic 210 relates to the memory mode or the MAC mode, and the scheduler 220 may transmit the mode selection signal to the command queue logic 210.

The memory command generator 230 may receive the command queue related to the memory mode of the PIM device 100 from the command queue logic 210. The memory command generator 230 may decode the command queue to generate and output the memory command signal M_CMD. The memory command signal M_CMD that is output from the memory command generator 230 may be transmitted to the PIM device 100. In an embodiment, the memory command signal M_CMD may include a memory read command signal and a memory write command signal. When the memory read command signal is output from the memory command generator 230, the PIM device 100 may perform the data read operation for the first memory bank 111 or the second memory bank 112. Data which are read out of the PIM device 100 may be transmitted to an external device through the data I/O pad 132. The read data that is output from the PIM device 100 may be transmitted to a host through the PIM controller 200. When the memory write command signal is output from the memory command generator 230, the PIM device 100 may perform the data write operation for the first memory bank 111 or the second memory bank 112. In such a case, data to be written into the PIM device 100 may be transmitted from the host to the PIM device 100 through the PIM controller 200. The write data that is input to the PIM device 100 may be transmitted to the first memory bank 111 or the second memory bank 112 through the data I/O pad 132.

The MAC command generator 240 may receive the command queue related to the MAC mode of the PIM device 100 from the command queue logic 210. The MAC command generator 240 may decode the command queue to generate and output the MAC command signals MAC_CMDs. The MAC command signals MAC_CMDs that is output from the MAC command generator 240 may be transmitted to the PIM device 100. The data read operation for the first memory bank 111 and the second memory bank 112 of the PIM device 100 may be performed by the MAC command signals MAC_CMDs that is output from the MAC command generator 240, and the MAC arithmetic operation of the MAC operator 120 may also be performed by the MAC command signals MAC_CMDs that is output from the MAC command generator 240. The MAC command signals MAC_CMDs and the MAC arithmetic operation of the PIM device 100 according to the MAC command signals MAC_CMDs will be described in detail with reference to FIG. 3.

The address generator 250 may receive address information from the command queue logic 210. The address generator 250 may generate the bank selection signal BS for selecting one of the first and second memory banks 111 and 112 and may transmit the bank selection signal BS to the PIM device 100. In addition, the address generator 250 may generate the row address signal ADDR_R and the column address signal ADDR_C for accessing a region (e.g., memory cells) in the first or second memory bank 111 or 112 and may transmit the row address signal ADDR_R and the column address signal ADDR_C to the PIM device 100.

FIG. 3 illustrates the MAC command MAC_CMDs signals that are output from the MAC command generator 240 included in the PIM system 1-1 according to the first embodiment of the present disclosure. As illustrated in FIG. 3, the MAC command signals MAC_CMDs may include first to sixth MAC command signals. In an embodiment, the first MAC command signal may be a first MAC read signal MAC_RD_BK0, the second MAC command signal may be a second MAC read signal MAC_RD_BK1, the third MAC command signal may be a first MAC input latch signal MAC_L1, the fourth MAC command signal may be a second MAC input latch signal MAC_L2, the fifth MAC command signal may be a MAC output latch signal MAC_L3, and the sixth MAC command signal may be a MAC latch reset signal MAC_L_RST.

The first MAC read signal MAC_RD_BK0 may control an operation for reading first data (e.g., weight data) out of the first memory bank 111 to transmit the first data to the MAC operator 120. The second MAC read signal MAC_RD_BK1 may control an operation for reading second data (e.g., vector data) out of the second memory bank 112 to transmit the second data to the MAC operator 120. The first MAC input latch signal MAC_L1 may control an input latch operation of the weight data transmitted from the first memory bank 111 to the MAC operator 120. The second MAC input latch signal MAC_L2 may control an input latch operation of the vector data transmitted from the second memory bank 112 to the MAC operator 120. If the input latch operations of the weight data and the vector data are performed, the MAC operator 120 may perform the MAC arithmetic operation to generate MAC result data corresponding to the result of the MAC arithmetic operation. The MAC output latch signal MAC_L3 may control an output latch operation of the MAC result data generated by the MAC operator 120. And, the MAC latch reset signal MAC_L_RST may control an output operation of the MAC result data generated by the MAC operator 120 and a reset operation of an output latch included in the MAC operator 120.

The PIM system 1-1 according to the present embodiment may be configured to perform a deterministic MAC arithmetic operation. The term “deterministic MAC arithmetic operation” used in the present disclosure may be defined as the MAC arithmetic operation performed in the PIM system 1-1 during a predetermined fixed time. Thus, the MAC commands MAC_CMDs transmitted from the PIM controller 200 to the PIM device 100 may be sequentially generated with fixed time intervals. Accordingly, the PIM controller 200 does not require any extra end signals of various operations executed for the MAC arithmetic operation to generate the MAC commands MAC_CMDs for controlling the MAC arithmetic operation. In an embodiment, latencies of the various operations executed by MAC command signals MAC_CMDs for controlling the MAC arithmetic operation may be set to have fixed values in order to perform the deterministic MAC arithmetic operation. In such a case, the MAC command signals MAC_CMDs may be sequentially output from the PIM controller 200 with fixed time intervals corresponding to the fixed latencies.

For example, the MAC command generator 240 is configured to output the first MAC command signal at a first point in time. The MAC command generator 240 is configured to output the second MAC command signal at a second point in time when a first latency elapses from the first point in time. The first latency is set as the time it takes to read the first data out of the first storage region based on the first MAC command and to output the first data to the MAC operator. The MAC command generator 240 is configured to output the third MAC command signal at a third point in time when a second latency elapses from the second point in time. The second latency is set as the time it takes to read the second data out of the second storage region based on the second MAC command signal and to output the MAC operator based on the third MAC command signal. The MAC command generator 240 is configured to output the fifth MAC command second data to the MAC operator. The MAC command generator 240 is configured to output the fourth MAC command signal at a fourth point in time when a third latency elapses from the third point in time. The third latency is set as the time it takes to latch the first data at a fifth point in time when a fourth latency elapses from the fourth point in time. The fourth latency is set as the time it takes to latch the second data in the MAC operator based on the fourth MAC command signal and to perform the MAC arithmetic operation of the first and second data which are latched in the MAC operator. The MAC command generator 240 is configured to output the sixth MAC command signal at a sixth point in time when a fifth latency elapses from the fifth point in time. The fifth latency is set as the time it takes to perform an output latch operation of MAC result data generated by the MAC arithmetic operation.

FIG. 4 illustrates an example of the MAC operator 120 of the PIM device 100 included in the PIM system 1-1 according to the first embodiment of the present disclosure. Referring to FIG. 4, MAC operator 120 may be configured to include a data input circuit 121, a MAC circuit 122, and a data output circuit 123. The data input circuit 121 may include a first input latch 121-1 and a second input latch 121-2. The MAC circuit 122 may include a multiplication logic circuit 122-1 and an addition logic circuit 122-2. The data output circuit 123 may include an output latch 123-1, a transfer gate 123-2, a delay circuit 123-3, and an inverter 123-4. In an embodiment, the first input latch 121-1, the second input latch 121-2, and the output latch 123-1 may be realized using flip-flops.

The data input circuit 121 of the MAC operator 120 may be synchronized with the first MAC input latch signal MAC_L1 to latch first data DA1 transferred from the first memory bank 111 to the MAC circuit 122 through an internal data transmission line. In addition, the data input circuit 121 of the MAC operator 120 may be synchronized with the second MAC input latch signal MAC_L2 to latch second data DA2 transferred from the second memory bank 112 to the MAC circuit 122 through another internal data transmission line. Because the first MAC input latch signal MAC_L1 and the second MAC input latch signal MAC_L2 are sequentially transmitted from the MAC command generator 240 of the PIM controller 200 to the MAC operator 120 of the PIM device 100 with a predetermined time interval, the second data DA2 may be input to the MAC circuit 122 of the MAC operator 120 after the first data DA1 is input to the MAC circuit 122 of the MAC operator 120.

The MAC circuit 122 may perform the MAC arithmetic operation of the first data DA1 and the second data DA2, input through the data input circuit 121. The multiplication logic circuit 122-1 of the MAC circuit 122 may include a plurality of multipliers 122-11. Each of the multipliers 122-11 may perform a multiplying calculation of the first data DA1 that is output from the first input latch 121-1 and the second data DA2 that is output from the second input latch 121-2 and may output the result of the multiplying calculation. Bit values constituting the first data DA1 may be separately input to the multipliers 122-11. Similarly, bit values constituting the second data DA2 may also be separately input to the multipliers 122-11. For example, if the first data DA1 is represented by an ‘N’-bit binary stream, the second data DA2 is represented by an ‘N’-bit binary stream, and the number of the multipliers 122-11 is ‘M’, then ‘N/M’-bit portions of the first data DA1 and ‘N/M’-bit portions of the second data DA2 may be input to each of the multipliers 122-11.

The addition logic circuit 122-2 of the MAC circuit 122 may include a plurality of adders 122-21. Although not shown in the drawings, the plurality of adders 122-21 may be disposed to provide a tree structure including a plurality of stages. Each of the adders 122-21 disposed at a first stage may receive two sets of multiplication result data from two of the multipliers 122-11 included in the multiplication logic circuit 122-1 and may perform an adding calculation of the two sets of multiplication result data to output the addition result data. Each of the adders 122-21 disposed at a second stage may receive two sets of addition result data from two of the adders 122-21 disposed at the first stage and may perform an adding calculation of the two sets of addition result data to output the addition result data. The adder 122-21 disposed at a last stage may receive two sets of addition result data from two adders 122-21 disposed at the previous stage and may perform an adding calculation of the two sets of addition result data to output the addition result data. Although not shown in the drawings, the addition logic circuit 122-2 may further include an additional adder for performing an accumulative adding calculation of MAC result data DA_MAC that is output from the adder 122-21 disposed at the last stage and previous MAC result data DA_MAC stored in the output latch 123-1 of the data output circuit 123.

The data output circuit 123 may output the MAC result data DA_MAC that is output from the MAC circuit 122 to a data transmission line. Specifically, the output latch 123-1 of the data output circuit 123 may be synchronized with the MAC output latch signal MAC_L3 to latch the MAC result data DA_MAC that is output from the MAC circuit 122 and to output the latched data of the MAC result data DA_MAC. The MAC result data DA_MAC that is output from the output latch 123-1 may be fed back to the MAC circuit 122 for the accumulative adding calculation. In addition, the MAC result data DA_MAC may be input to the transfer gate 123-2. The output latch 123-1 may be initialized if a latch reset signal LATCH_RST is input to the output latch 123-1. In such a case, all of data latched by the output latch 123-1 may be removed. In an embodiment, the latch reset signal LATCH_RST may be activated by generation of the MAC latch reset signal MAC_L_RST and may be input to the output latch 123-1.

The MAC latch reset signal MAC_L_RST that is output from the MAC command generator 240 may be input to the transfer gate 123-2, the delay circuit 123-3, and the inverter 123-4. The inverter 123-4 may inversely buffer the MAC latch reset signal MAC_L_RST to output the inversely buffered signal of the MAC latch reset signal MAC_L_RST to the transfer gate 123-2. The transfer gate 123-2 may transfer the MAC result data DA_MAC from the output latch 123-1 to the data transmission line in response to the MAC latch reset signal MAC_L_RST. The delay circuit 123-3 may delay the MAC latch reset signal MAC_L_RST by a certain time to generate and output a latch control signal PINSTB.

FIG. 5 illustrates an example of the MAC arithmetic operation performed in the PIM system 1-1 according to the first embodiment of the present disclosure. As illustrated in FIG. 5, the MAC arithmetic operation performed by the PIM system 1-1 may be executed though a matrix calculation. Specifically, the PIM device 100 may execute a matrix multiplying calculation of an ‘M× N’ weight matrix (e.g., ‘8×8’ weight matrix) and a ‘N×1’ vector matrix (e.g., ‘8×1’ vector matrix) according to control of the PIM controller 200 (where, ‘M’ and ‘N’ are natural numbers). Elements W0.0, . . . , and W7.7 constituting the weight matrix may correspond to the first data DA1 that is input to the MAC operator 120 from the first memory bank 111. Elements X0.0, . . . , and X7.0 constituting the vector matrix may correspond to the second data DA2 that is input to the MAC operator 120 from the second memory bank 112. Each of the elements W0.0, . . . , and W7.7 constituting the weight matrix may be represented by a binary stream with a plurality of bit values. In addition, each of the elements X0.0, . . . , and X7.0 constituting the vector matrix may also be represented by a binary stream with a plurality of bit values. The number of bits included in each of the elements W0.0, . . . , and W7.7 constituting the weight matrix may be equal to the number of bits included in each of the elements X0.0, . . . , and X7.0 constituting the vector matrix.

The matrix multiplying calculation of the weight matrix and the vector matrix may be appropriate for a multilayer perceptron-type neural network structure (hereinafter, referred to as an ‘MLP-type neural network’). In general, the MLP-type neural network for executing deep learning may include an input layer, a plurality of hidden layers (e.g., at least three hidden layers), and an output layer. The matrix multiplying calculation (i.e., the MAC arithmetic operation) of the weight matrix and the vector matrix illustrated in FIG. 5 may be performed in one of the hidden layers. In a first hidden layer of the plurality of hidden layers, the MAC arithmetic operation may be performed using vector data that is input to the first hidden layer. However, in each of second to last hidden layers among the plurality of hidden layers, the MAC arithmetic operation may be performed using a calculation result of the previous hidden layer as the vector data.

FIG. 6 is a flowchart illustrating processes of the MAC arithmetic operation described with reference to FIG. 5, which are performed in the PIM system 1-1 according to the first embodiment of the present disclosure. In addition, FIGS. 7 to 13 are block diagrams illustrating the processes of the MAC arithmetic operation illustrated in FIG. 5, which are performed in the PIM system 1-1 according to the first embodiment of the present disclosure. Referring to FIGS. 6 to 13, before the MAC arithmetic operation is performed, the first data (i.e., the weight data) may be written into the first memory bank 111 at a step 301. Thus, the weight data may be stored in the first memory bank 111 of the PIM device 100. In the present embodiment, it may be assumed that the weight data are the elements W0.0, . . . , and W7.7 constituting the weight matrix of FIG. 5. The integer before the decimal point is one less than a row number, and the integer after the decimal point is one less than a column number. Thus, for example, the weight W0.0 represents the element of the first row and the first column of the weight matrix.

At a step 302, whether an inference is requested may be determined. An inference request signal may be transmitted from an external device located outside of the PIM system 1-1 to the PIM controller 200 of the PIM system 1-1. An inference request, in some instances, may be based on user input. An inference request may initiate a calculation performed by the PIM system 1-1 to reach a determination based on input data. In an embodiment, if no inference request signal is transmitted to the PIM controller 200, the PIM system 1-1 may be in a standby mode until the inference request signal is transmitted to the PIM controller 200. Alternatively, if no inference request signal is transmitted to the PIM controller 200, the PIM system 1-1 may perform operations (e.g., data read/write operations) other than the MAC arithmetic operation in the memory mode until the inference request signal is transmitted to the PIM controller 200. In the present embodiment, it may be assumed that the second data (i.e., the vector data) are transmitted together with the inference request signal. In addition, it may be assumed that the vector data are the elements X0.0, . . . , and X7.0 constituting the vector matrix of FIG. 5. If the inference request signal is transmitted to the PIM controller 200 at the step 302, then the PIM controller 200 may write the vector data transmitted with the inference request signal into the second memory bank 112 at a step 303. Accordingly, the vector data may be stored in the second memory bank 112 of the PIM device 100.

At a step 304, the MAC command generator 240 of the PIM controller 200 may generate and transmit the first MAC read signal MAC_RD_BK0 to the PIM device 100, as illustrated in FIG. 7. In such a case, the address generator 250 of the PIM controller 200 may generate and transmit the bank selection signal BS and the row/column address ADDR_R/ADDR_C to the PIM device 100. The bank selection signal BS may be generated to select the first memory bank 111 of the first and second memory banks 111 and 112. Thus, the first MAC read signal MAC_RD_BK0 may control the data read operation for the first memory bank 111 of the PIM device 100. The first memory bank 111 may output and transmit the elements W0.0, . . . , and W0.7 in the first row of the weight matrix of the weight data stored in a region of the first memory bank 111, which is selected by the row/column address ADDR_R/ADDR_C, to the MAC operator 120 in response to the first MAC read signal MAC_RD_BK0. In an embodiment, the data transmission from the first memory bank 111 to the MAC operator 120 may be executed through a global input/output (hereinafter, referred to as ‘GIO’) line which is provided as a data transmission path in the PIM device 100. Alternatively, the data transmission from the first memory bank 111 to the MAC operator 120 may be executed through a first bank input/output (hereinafter, referred to as ‘BIO’) line which is provided specifically for data transmission between the first memory bank 111 and the MAC operator 120.

At a step 305, the MAC command generator 240 of the PIM controller 200 may generate and transmit the second MAC read signal MAC_RD_BK1 to the PIM device 100, as illustrated in FIG. 8. In such a case, the address generator 250 of the PIM controller 200 may generate and transmit the bank selection signal BS for selecting the second memory bank 112 and the row/column address ADDR_R/ADDR_C to the PIM device 100. The second MAC read signal MAC_RD_BK1 may control the data read operation for the second memory bank 112 of the PIM device 100. The second memory bank 112 may output and transmit the elements X0.0, . . . , and X7.0 in the first column of the vector matrix corresponding to the vector data stored in a region of the second memory bank 112, which is selected by the row/column address ADDR_R/ADDR_C, to the MAC operator 120 in response to the second MAC read signal MAC_RD_BK1. In an embodiment, the data transmission from the second memory bank 112 to the MAC operator 120 may be executed through the GIO line in the PIM device 100. Alternatively, the data transmission from the second memory bank 112 to the MAC operator 120 may be executed through a second BIO line which is provided specifically for data transmission between the second memory bank 112 and the MAC operator 120.

At a step 306, the MAC command generator 240 of the PIM controller 200 may generate and transmit the first MAC input latch signal MAC_L1 to the PIM device 100, as illustrated in FIG. 9. The first MAC input latch signal MAC_L1 may control the input latch operation of the first data for the MAC operator 120 of the PIM device 100. The elements W0.0, . . . , and W0.7 in the first row of the weight matrix may be input to the MAC circuit 122 of the MAC operator 120 by the input latch operation, as illustrated in FIG. 11. The MAC circuit 122 may include the plurality of multipliers 122-11 (e.g., eight multipliers 122-11), the number of which is equal to the number of columns of the weight matrix. In such a case, the elements W0.0, . . . , and W0.7 in the first row of the weight matrix may be input to the eight multipliers 122-11, respectively.

At a step 307, the MAC command generator 240 of the PIM controller 200 may generate and transmit the second MAC input latch signal MAC_L2 to the PIM device 100, as illustrated in FIG. 10. The second MAC input latch signal MAC_L2 may control the input latch operation of the second data for the MAC operator 120 of the PIM device 100. The elements X0.0, . . . , and X7.0 in the first column of the vector matrix may be input to the MAC circuit 122 of the MAC operator 120 by the input latch operation, as illustrated in FIG. 11. In such a case, the elements X0.0, . . . , and X7.0 in the first column of the vector matrix may be input to the eight multipliers 122-11, respectively.

At a step 308, the MAC circuit 122 of the MAC operator 120 may perform the MAC arithmetic operation of an R^(th) row of the weight matrix and the first column of the vector matrix, which are input to the MAC circuit 122. An initial value of ‘R’ may be set as ‘1’. Thus, the MAC arithmetic operation of the first row of the weight matrix and the first column of the vector matrix may be performed a first time. For example, the scalar product is calculated of the Rth ‘1×N’ row vector of the ‘M×N’ weight matrix and the ‘11×1’ vector matrix as an ‘R×1’ element of the ‘M×1’ MAC result matrix. For R=1, the scalar product of the first row of the weight matrix and the first column of the vector matrix shown in FIG. 5 is W0.0*X0.0+W0.1*X1.0+W0.2*X2.0+W0.3*X3.0+W0.4*X4.0+W0.5*X5.0+W0.6*X6.0+W0.7*X7.0. Specifically, each of the multipliers 122-11 of the multiplication logic circuit 122-1 may perform a multiplying calculation of the inputted data, and the result data of the multiplying calculation may be input to the addition logic circuit 122-2. The addition logic circuit 122-2, as illustrated in FIG. 11, may include four adders 122-21A disposed at a first stage, two adders 122-21B disposed at a second stage, and an adder 122-21C disposed at a third stage.

Each of the adders 122-21A disposed at the first stage may receive output data of two of the multipliers 122-11 and may perform an adding calculation of the output data of the two multipliers 122-11 to output the result of the adding calculation. Each of the adders 122-21B disposed at the second stage may receive output data of two of the adders 122-21A disposed at the first stage and may perform an adding calculation of the output data of the two adders 122-21A to output the result of the adding calculation. The adder 122-21C disposed at the third stage may receive output data of two of the adders 122-21B disposed at the second stage and may perform an adding calculation of the output data of the two adders 122-21B to output the result of the adding calculation. The output data of the addition logic circuit 122-2 may correspond to result data (i.e., MAC result data) of the MAC arithmetic operation of the first row included in the weight matrix and the column included in the vector matrix. Thus, the output data of the addition logic circuit 122-2 may correspond to an element MAC0.0 located at a first row of an ‘8×1’ MAC result matrix with eight elements of MAC0.0, . . . , and MAC7.0, as illustrated in FIG. 5. The output data MAC0.0 of the addition logic circuit 122-2 may be input to the output latch 123-1 disposed in the data output circuit 123 of the MAC operator 120, as described with reference to FIG. 4.

At a step 309, the MAC command generator 240 of the PIM controller 200 may generate and transmit the MAC output latch signal MAC_L3 to the PIM device 100, as illustrated in FIG. 12. The MAC output latch signal MAC_L3 may control the output latch operation of the MAC result data MAC0.0 performed by the MAC operator 120 of the PIM device 100. The MAC result data MAC0.0 that is input from the MAC circuit 122 of the MAC operator 120 may be output from the output latch 123-1 in synchronization with the MAC output latch signal MAC_L3, as described with reference to FIG. 4. The MAC result data MAC0.0 that is output from the output latch 123-1 may be input to the transfer gate 123-2 of the data output circuit 123.

At a step 310, the MAC command generator 240 of the PIM controller 200 may generate and transmit the MAC latch reset signal MAC_L_RST to the PIM device 100, as illustrated in FIG. 13. The MAC latch reset signal MAC_L_RST may control an output operation of the MAC result data MAC0.0 generated by the MAC operator 120 and a reset operation of the output latch included in the MAC operator 120. As described with reference to FIG. 4, the transfer gate 123-2 receiving the MAC result data MAC0.0 from the output latch 123-1 of the MAC operator 120 may be synchronized with the MAC latch reset signal MAC_L_RST to output the MAC result data MAC0.0. In an embodiment, the MAC result data MAC0.0 that is output from the MAC operator 120 may be stored into the first memory bank 111 or the second memory bank 112 through the first BIO line or the second BIO line in the PIM device 100.

At a step 311, the row number ‘R’ of the weight matrix for which the MAC arithmetic operation is performed may be increased by ‘1’. Because the MAC arithmetic operation for the first row among the first to eight rows of the weight matrix has been performed during the previous steps, the row number of the weight matrix may change from ‘1’ to ‘2’ at the step 311. At a step 312, whether the row number changed at the step 311 is greater than the row number of the last row (i.e., the eighth row of the current example) of the weight matrix may be determined. Because the row number of the weight matrix is changed to ‘2’ at the step 311, a process of the MAC arithmetic operation may be fed back to the step 304.

If the process of the MAC arithmetic operation is fed back to the step 304 from the step 312, then the same processes as described with reference to the steps 304 to 310 may be executed again for the increased row number of the weight matrix. That is, as the row number of the weight matrix changes from ‘1’ to ‘2’, the MAC arithmetic operation may be performed for the second row of the weight matrix instead of the first row of the weight matrix with the vector matrix. If the process of the MAC arithmetic operation is fed back to the step 304 at the step 312, then the processes from the step 304 to the step 311 may be iteratively performed until the MAC arithmetic operation is performed for all of the rows of the weight matrix with the vector matrix. If the MAC arithmetic operation for the eighth row of the weight matrix terminates and the row number of the weight matrix changes from ‘8’ to ‘9’ at the step 311, the MAC arithmetic operation may terminate because the row number of ‘9’ is greater than the last row number of ‘8’ at the step 312.

FIG. 14 illustrates another example of a MAC arithmetic operation performed in the PIM system 1-1 according to the first embodiment of the present disclosure. As illustrated in FIG. 14, the MAC arithmetic operation performed by the PIM system 1-1 may further include an adding calculation of the MAC result matrix and a bias matrix. Specifically, as described with reference to FIG. 5, the PIM device 100 may execute the matrix multiplying calculation of the ‘8×8’ weight matrix and the ‘8×1’ vector matrix according to control of the PIM controller 200. As a result of the matrix multiplying calculation of the ‘8×8’ weight matrix and the ‘8×1’ vector matrix, the ‘8×1’ MAC result matrix with the eight elements MAC0.0, . . . , and MAC7.0 may be generated. The ‘8×1’ MAC result matrix may be added to a ‘8×1’ bias matrix. The ‘8×1’ bias matrix may have elements B0.0, . . . , and B7.0 corresponding to bias data. The bias data may be set to reduce an error of the MAC result matrix. As a result of the adding calculation of the MAC result matrix and the bias matrix, a ‘8×1’ biased result matrix with eight elements Y0.0, . . . , and Y7.0 may be generated.

FIG. 15 is a flowchart illustrating processes of the MAC arithmetic operation described with reference to FIG. 14 in the PIM system 1-1 according to the first embodiment of the present disclosure. Moreover, FIG. 16 illustrates an example of a configuration of a MAC operator 120-1 for performing the MAC arithmetic operation of FIG. 14 in the PIM system 1-1 according to the first embodiment of the present disclosure. In FIG. 16, the same reference numerals or the same reference symbols as used in FIG. 4 denote the same elements, and the detailed descriptions of the same elements as indicated in the previous embodiment will be omitted hereinafter. Referring to FIG. 15, the first data (i.e., the weight data) may be written into the first memory bank 111 at a step 321 to perform the MAC arithmetic operation in the PIM device 100. Thus, the weight data may be stored in the first memory bank 111 of the PIM device 100. In the present embodiment, it may be assumed that the weight data are the elements W0.0, . . . , and W7.7 constituting the weight matrix of FIG. 14.

At a step 322, whether an inference is requested may be determined. An inference request signal may be transmitted from an external device located outside of the PIM system 1-1 to the PIM controller 200 of the PIM system 1-1. In an embodiment, if no inference request signal is transmitted to the PIM controller 200, the PIM system 1-1 may be in a standby mode until the inference request signal is transmitted to the PIM controller 200. Alternatively, if no inference request signal is transmitted to the PIM controller 200, the PIM system 1-1 may perform operations (e.g., data read/write operations) other than the MAC arithmetic operation in the memory mode until the inference request signal is transmitted to the PIM controller 200. In the present embodiment, it may be assumed that the second data (i.e., the vector data) are transmitted together with the inference request signal. In addition, it may be assumed that the vector data are the elements X0.0, . . . , and X7.0 constituting the vector matrix of FIG. 14. If the inference request signal is transmitted to the PIM controller 200 at the step 322, the PIM controller 200 may write the vector data transmitted with the inference request signal into the second memory bank 112 at a step 323. Accordingly, the vector data may be stored in the second memory bank 112 of the PIM device 100.

At a step 324, the output latch of the MAC operator may be initially set to have the bias data and the initially set bias data may be fed back to an accumulative adder of the MAC operator. This process is executed to perform the matrix adding calculation of the MAC result matrix and the bias matrix, which is described with reference to FIG. 14. In other words, the output latch 123-1 in the data output circuit 123-A of the MAC operator (120-1) is set to have the bias data. Because the matrix multiplying calculation is executed for the first row of the weight matrix, the output latch 123-1 may be initially set to have the element B0.0 located at a cross point of the first row and the first column of the bias matrix as the bias data. The output latch 123-1 may output the bias data B0.0, and the bias data B0.0 that is output from the output latch 123-1 may be input to the accumulative adder 122-21D of the addition logic circuit 122-2, as illustrated in FIG. 16.

In an embodiment, in order to output the bias data B0.0 out of the output latch 123-1 and to feed back the bias data B0.0 to the accumulative adder 122-21D, the MAC command generator 240 of the PIM controller 200 may transmit the MAC output latch signal MAC_L3 to the MAC operator 120-1 of the PIM device 100. When a subsequent MAC arithmetic operation is performed, the accumulative adder 122-21D of the MAC operator 120-1 may add the MAC result data MAC0.0 that is output from the adder 122-21C disposed at the last stage to the bias data B0.0 which is fed back from the output latch 123-1 to generate the biased result data Y0.0 and may output the biased result data Y0.0 to the output latch 123-1. The biased result data Y0.0 may be output from the output latch 123-1 in synchronization with the MAC output latch signal MAC_L3 transmitted in a subsequent process.

In a step 325, the MAC command generator 240 of the PIM controller 200 may generate and transmit the first MAC read signal MAC_RD_BK0 to the PIM device 100. In addition, the address generator 250 of the PIM controller 200 may generate and transmit the bank selection signal BS and the row/column address ADDR_R/ADDR_C to the PIM device 100. The step 325 may be executed in the same way as described with reference to FIG. 7. In a step 326, the MAC command generator 240 of the PIM controller 200 may generate and transmit the second MAC read signal MAC_RD_BK1 to the PIM device 100. In addition, the address generator 250 of the PIM controller 200 may generate and transmit the bank selection signal BS for selecting the second memory bank 112 and the row/column address ADDR_R/ADDR_C to the PIM device 100. The step 326 may be executed in the same way as described with reference to FIG. 8.

At a step 327, the MAC command generator 240 of the PIM controller 200 may generate and transmit the first MAC input latch signal MAC_L1 to the PIM device 100. The step 327 may be executed in the same way as described with reference to FIG. 9. The first MAC input latch signal MAC_L1 may control the input latch operation of the first data for the MAC operator 120 of the PIM device 100. The input latch operation of the first data may be performed in the same way as described with reference to FIG. 11. At a step 328, the MAC command generator 240 of the PIM controller 200 may generate and transmit the second MAC input latch signal MAC_L2 to the PIM device 100. The step 328 may be executed in the same way as described with reference to FIG. 10. The second MAC input latch signal MAC_L2 may control the input latch operation of the second data for the MAC operator 120 of the PIM device 100. The input latch operation of the second data may be performed in the same way as described with reference to FIG. 11.

At a step 329, the MAC circuit 122 of the MAC operator 120 may perform the MAC arithmetic operation of an R^(th) row of the weight matrix and the first column of the vector matrix, which are input to the MAC circuit 122. An initial value of ‘R’ may be set as ‘1’. Thus, the MAC arithmetic operation of the first row of the weight matrix and the first column of the vector matrix may be performed a first time. Specifically, each of the multipliers 122-11 of the multiplication logic circuit 122-1 may perform a multiplying calculation of the inputted data, and the result data of the multiplying calculation may be input to the addition logic circuit 122-2. The addition logic circuit 122-2 may include the four adders 122-21A disposed at the first stage, the two adders 122-21B disposed at the second stage, the adder 122-21C disposed at the third stage, and the accumulative adder 122-21D, as illustrated in FIG. 16. The accumulative adder 122-21D may add output data of the adder 122-21C to feedback data fed back from the output latch 123-1 to output the result of the adding calculation. The output data of the adder 122-21C may be the matrix multiplying result MAC0.0, which corresponds to the result of the matrix multiplying calculation of the first row of the weight matrix and the first column of the vector matrix. The accumulative adder 122-21D may add the output data MAC0.0 of the adder 122-21C to the bias data B0.0 fed back from the output latch 123-1 to output the result of the adding calculation. The output data Y0.0 of the accumulative adder 122-21D may be input to the output latch 123 disposed in a data output circuit 123-A of the MAC operator 120-1.

At a step 330, the MAC command generator 240 of the PIM controller 200 may generate and transmit the MAC output latch signal MAC_L3 to the PIM device 100. The step 330 may be executed in the same way as described with reference to FIG. 12. The MAC output latch signal MAC_L3 may control the output latch operation of the MAC result data MAC0.0, which is performed by the MAC operator 120-1 of the PIM device 100. The biased result data Y0.0 transmitted from the MAC circuit 122 of the MAC operator 120 to the output latch 123-1 may be output from the output latch 123-1 in synchronization with the MAC output latch signal MAC_L3. The biased result data Y0.0 that is output from the output latch 123 may be input to the transfer gate 123-2.

At a step 331, the MAC command generator 240 of the PIM controller 200 may generate and transmit the MAC latch reset signal MAC_L_RST to the PIM device 100. The step 331 may be executed in the same way as described with reference to FIG. 13. The MAC latch reset signal MAC_L_RST may control an output operation of the biased result data Y0.0 generated by the MAC operator 120 and a reset operation of the output latch 123-1 included in the MAC operator 120. The transfer gate 123-2 receiving the biased result data Y0.0 from the output latch 123-1 of the data output circuit 123-A included in the MAC operator 120 may be synchronized with the MAC latch reset signal MAC_L_RST to output the biased result data Y0.0. In an embodiment, the biased result data Y0.0 that is output from the MAC operator 120 may be stored into the first memory bank 111 or the second memory bank 112 through the first BIO line or the second BIO line in the PIM device 100.

At a step 332, the row number ‘R’ of the weight matrix for which the MAC arithmetic operation is performed may be increased by ‘1’. Because the MAC arithmetic operation for the first row among the first to eight rows of the weight matrix has been performed during the previous steps, the row number of the weight matrix may change from ‘1’ to ‘2’ at the step 332. At a step 333, whether the row number changed at the step 332 is greater than the row number of the last row (i.e., the eighth row of the current example) of the weight matrix may be determined. Because the row number of the weight matrix is changed to ‘2’ at the step 332, a process of the MAC arithmetic operation may be fed back to the step 324.

If the process of the MAC arithmetic operation is fed back to the step 324 from the step 333, then the same processes as described with reference to the steps 324 to 331 may be executed again for the increased row number of the weight matrix. That is, as the row number of the weight matrix changes from ‘1’ to ‘2’, the MAC arithmetic operation may be performed for the second row of the weight matrix instead of the first row of the weight matrix with the vector matrix and the bias data B0.0 in the output latch 123-1 initially set at the step 324 may be changed into the bias data B1.0. If the process of the MAC arithmetic operation is fed back to the step 324 at the step 333, the processes from the step 324 to the step 332 may be iteratively performed until the MAC arithmetic operation is performed for all of the rows of the weight matrix with the vector matrix. If the MAC arithmetic operation for the eighth row of the weight matrix terminates and the row number of the weight matrix changes from ‘8’ to ‘9’ at the step 332, the MAC arithmetic operation may terminate because the row number of ‘9’ is greater than the last row number of ‘8’ at the step 333.

FIG. 17 illustrates yet another example of a MAC arithmetic operation performed in the PIM system 1-1 according to the first embodiment of the present disclosure. As illustrated in FIG. 17, the MAC arithmetic operation performed by the PIM system 1-1 may further include a process for applying the biased result matrix to an activation function. Specifically, as described with reference to FIG. 14, the PIM device 100 may execute the matrix multiplying calculation of the ‘8×8’ weight matrix and the ‘8×1’ vector matrix according to control of the PIM controller 200 to generate the MAC result matrix. In addition, the MAC result matrix may be added to the bias matrix to generate biased result matrix.

The biased result matrix may be applied to the activation function. The activation function means a function which is used to calculate a unique output value by comparing a MAC calculation value with a critical value in an MLP-type neural network. In an embodiment, the activation function may be a unipolar activation function which generates only positive output values or a bipolar activation function which generates negative output values as well as positive output values. In different embodiments, the activation function may include a sigmoid function, a hyperbolic tangent (Tan h) function, a rectified linear unit (ReLU) function, a leaky ReLU function, an identity function, and a maxout function.

FIG. 18 is a flowchart illustrating processes of the MAC arithmetic operation described with reference to FIG. 17 in the PIM system 1-1 according to the first embodiment of the present disclosure. Moreover, FIG. 19 illustrates an example of a configuration of a MAC operator 120-2 for performing the MAC arithmetic operation of FIG. 17 in the PIM system 1-1 according to the first embodiment of the present disclosure. In FIG. 19, the same reference numerals or the same reference symbols as used in FIG. 4 denote the same elements, and the detailed descriptions of the same elements as mentioned in the previous embodiment will be omitted hereinafter. Referring to FIG. 18, the first data (i.e., the weight data) may be written into the first memory bank 111 at a step 341 to perform the MAC arithmetic operation in the PIM device 100. Thus, the weight data may be stored in the first memory bank 111 of the PIM device 100. In the present embodiment, it may be assumed that the weight data are the elements W0.0, . . . , and W7.7 constituting the weight matrix of FIG. 17.

At a step 342, whether an inference is requested may be determined. An inference request signal may be transmitted from an external device located outside of the PIM system 1-1 to the PIM controller 200 of the PIM system 1-1. In an embodiment, if no inference request signal is transmitted to the PIM controller 200, the PIM system 1-1 may be in a standby mode until the inference request signal is transmitted to the PIM controller 200. Alternatively, if no inference request signal is transmitted to the PIM controller 200, the PIM system 1-1 may perform operations (e.g., the data read/write operations) other than the MAC arithmetic operation in the memory mode until the inference request signal is transmitted to the PIM controller 200. In the present embodiment, it may be assumed that the second data (i.e., the vector data) are transmitted together with the inference request signal. In addition, it may be assumed that the vector data are the elements X0.0, . . . , and X7.0 constituting the vector matrix of FIG. 17. If the inference request signal is transmitted to the PIM controller 200 at the step 342, then the PIM controller 200 may write the vector data transmitted with the inference request signal into the second memory bank 112 at a step 343. Accordingly, the vector data may be stored in the second memory bank 112 of the PIM device 100.

At a step 344, an output latch of a MAC operator may be initially set to have bias data and the initially set bias data may be fed back to an accumulative adder of the MAC operator. This process is executed to perform the matrix adding calculation of the MAC result matrix and the bias matrix, which is described with reference to FIG. 17. That is, as illustrated in FIG. 19, the output latch 123-1 of the MAC operator (120-2 of FIG. 19) may be initially set to have the bias data of the bias matrix. Because the matrix multiplying calculation is executed for the first row of the weight matrix, the element B0.0 located at first row and the first column of the bias matrix may be initially set as the bias data in the output latch 123-1. The output latch 123-1 may output the bias data B0.0, and the bias data B0.0 that is output from the output latch 123-1 may be input to the accumulative adder 122-21D of the MAC operator 120-2.

In an embodiment, in order to output the bias data B0.0 out of the output latch 123-1 and to feed back the bias data B0.0 to the accumulative adder 122-21D, the MAC command generator 240 of the PIM controller 200 may transmit the MAC output latch signal MAC_L3 to the MAC operator 120-2 of the PIM device 100. When a subsequent MAC arithmetic operation is performed, the accumulative adder 122-21D of the MAC operator 120-2 may add the MAC result data MAC0.0 that is output from the adder 122-21C disposed at the last stage to the bias data B0.0 which is fed back from the output latch 123-1 to generate the biased result data Y0.0 and may output the biased result data Y0.0 to the output latch 123-1. As illustrated in FIG. 19, the biased result data Y0.0 may be transmitted from the output latch 123-1 to an activation function logic circuit 123-5 disposed in a data output circuit 123-B of the MAC operator 120-2 in synchronization with the MAC output latch signal MAC_L3 transmitted in a subsequent process.

In a step 345, the MAC command generator 240 of the PIM controller 200 may generate and transmit the first MAC read signal MAC_RD_BK0 to the PIM device 100. In addition, the address generator 250 of the PIM controller 200 may generate and transmit the bank selection signal BS and the row/column address ADDR_R/ADDR_C to the PIM device 100. The step 345 may be executed in the same way as described with reference to FIG. 7. In a step 346, the MAC command generator 240 of the PIM controller 200 may generate and transmit the second MAC read signal MAC_RD_BK1 to the PIM device 100. In addition, the address generator 250 of the PIM controller 200 may generate and transmit the bank selection signal BS for selecting the second memory bank 112 and the row/column address ADDR_R/ADDR_C to the PIM device 100. The step 346 may be executed in the same way as described with reference to FIG. 8.

At a step 347, the MAC command generator 240 of the PIM controller 200 may generate and transmit the first MAC input latch signal MAC_L1 to the PIM device 100. The step 347 may be executed in the same way as described with reference to FIG. 9. The first MAC input latch signal MAC_L1 may control the input latch operation of the first data for the MAC operator 120 of the PIM device 100. The input latch operation of the first data may be performed in the same way as described with reference to FIG. 11. At a step 348, the MAC command generator 240 of the PIM controller 200 may generate and transmit the second MAC input latch signal MAC_L2 to the PIM device 100. The step 348 may be executed in the same way as described with reference to FIG. 10. The second MAC input latch signal MAC_L2 may control the input latch operation of the second data for the MAC operator 120 of the PIM device 100. The input latch operation of the second data may be performed in the same way as described with reference to FIG. 11.

At a step 349, the MAC circuit 122 of the MAC operator 120 may perform the MAC arithmetic operation of an R^(th) row of the weight matrix and the first column of the vector matrix, which are input to the MAC circuit 122. An initial value of ‘R’ may be set as ‘1’. Thus, the MAC arithmetic operation of the first row of the weight matrix and the first column of the vector matrix may be performed a first time. Specifically, each of the multipliers 122-11 of the multiplication logic circuit 122-1 may perform a multiplying calculation of the inputted data, and the result data of the multiplying calculation may be input to the addition logic circuit 122-2. The addition logic circuit 122-2 may include the four adders 122-21A disposed at the first stage, the two adders 122-21B disposed at the second stage, the adder 122-21C disposed at the third stage, and the accumulative adder 122-21D, as illustrated in FIG. 19. The accumulative adder 122-21D may add output data of the adder 122-21C to feedback data fed back from the output latch 123-1 to output the result of the adding calculation. The output data of the adder 122-21C may be the element MAC0.0 of the ‘8×1’ MAC result matrix, which corresponds to the result of the matrix multiplying calculation of the first row of the weight matrix and the first column of the vector matrix. The accumulative adder 122-21D may add the output data MAC0.0 of the adder 122-21C to the bias data B0.0 fed back from the output latch 123-1 to output the result of the adding calculation. The output data Y0.0 of the accumulative adder 122-21D may be input to the output latch 123-1 disposed in the data output circuit 123-A of the MAC operator 120.

At a step 350, the MAC command generator 240 of the PIM controller 200 may generate and transmit the MAC output latch signal MAC_L3 to the PIM device 100. The step 350 may be executed in the same way as described with reference to FIG. 12. The MAC output latch signal MAC_L3 may control the output latch operation of the output latch 123-1 included in the MAC operator 120 of the PIM device 100. The biased result data Y0.0 transmitted from the MAC circuit 122 of the MAC operator 120 to the output latch 123-1 may be output from the output latch 123-1 in synchronization with the MAC output latch signal MAC_L3. The biased result data Y0.0 that is output from the output latch 123-1 may be input to the activation function logic circuit 123-5. At a step 351, the activation function logic circuit 123-5 may apply an activation function to the biased result data Y0.0 to generate a final output value, and the final output value may be input to the transfer gate (123-2 of FIG. 4). This, for example, is the final output value for the current of R which is incremented in step 354.

At a step 352, the MAC command generator 240 of the PIM controller 200 may generate and transmit the MAC latch reset signal MAC_L_RST to the PIM device 100. The step 352 may be executed in the same way as described with reference to FIG. 13. The MAC latch reset signal MAC_L_RST may control an output operation of the final output value generated by the MAC operator 120 and a reset operation of the output latch 123-1 included in the MAC operator 120. The transfer gate 123-2 receiving the final output value from the activation function logic circuit 123-5 of the data output circuit 123-B included in the MAC operator 120 may be synchronized with the MAC latch reset signal MAC_L_RST to output the final output value. In an embodiment, the final output value that is output from the MAC operator 120 may be stored into the first memory bank 111 or the second memory bank 112 through the first BIO line or the second BIO line in the PIM device 100.

At a step 353, the row number ‘R’ of the weight matrix for which the MAC arithmetic operation is performed may be increased by ‘1’. Because the MAC arithmetic operation for the first row among the first to eight rows of the weight matrix has been performed during the previous steps, the row number of the weight matrix may change from ‘1’ to ‘2’ at the step 353. At a step 354, whether the row number changed at the step 353 is greater than the row number of the last row (i.e., the eighth row) of the weight matrix may be determined. Because the row number of the weight matrix is changed to ‘2’ at the step 353, a process of the MAC arithmetic operation may be fed back to the step 344.

If the process of the MAC arithmetic operation is fed back to the step 344 from the step 354, the same processes as described with reference to the steps 344 to 354 may be executed again for the increased row number of the weight matrix. That is, as the row number of the weight matrix changes from ‘1’ to ‘2’, the MAC arithmetic operation may be performed for the second row of the weight matrix instead of the first row of the weight matrix with the vector matrix, and the bias data B0.0 in the output latch 123-1 initially set at the step 344 may be changed to the bias data B1.0. If the process of the MAC arithmetic operation is fed back to the step 344 from the step 354, the processes from the step 344 to the step 354 may be iteratively performed until the MAC arithmetic operation is performed for all of the rows of the weight matrix with the vector matrix. For an embodiment, a plurality of final output values, namely, one final output value for each incremented value of R, represents an ‘N×1’ final result matrix. If the MAC arithmetic operation for the eighth row of the weight matrix terminates and the row number of the weight matrix changes from ‘8’ to ‘9’ at the step 354, the MAC arithmetic operation may terminate because the row number of ‘9’ is greater than the last row number of ‘8’ at the step 354.

FIG. 20 is a block diagram illustrating a PIM system 1-2 according to a second embodiment of the present disclosure. In FIG. 20, the same reference numerals or the same reference symbols as used in FIG. 2 denote the same elements. As illustrated in FIG. 20, the PIM system 1-2 may be configured to include a PIM device 400 and a PIM controller 500. The PIM device 400 may be configured to include a memory bank (BANK) 411 corresponding to a storage region, a global buffer 412, a MAC operator 420, an interface (I/F) 431, and a data input/output (I/O) pad 432. For an embodiment, the MAC operator 420 represents a MAC operator circuit. The memory bank (BANK) 411 and the MAC operator 420 included in the PIM device 400 may constitute one MAC unit. In another embodiment, the PIM device 400 may include a plurality of MAC units. The memory bank (BANK) 411 may represent a memory region for storing data, for example, a DRAM device. The global buffer 412 may also represent a memory region for storing data, for example, a DRAM device or an SRAM device. The memory bank (BANK) 411 may be a component unit which is independently activated and may be configured to have the same data bus width as data I/O lines in the PIM device 400. In an embodiment, the memory bank 411 may operate through interleaving such that an active operation of the memory bank 411 is performed in parallel while another memory bank is selected. The memory bank 411 may include at least one cell array which includes memory unit cells located at cross points of a plurality of rows and a plurality of columns.

Although not shown in the drawings, a core circuit may be disposed adjacent to the memory bank 411. The core circuit may include X-decoders XDECs and Y-decoders/IO circuits YDEC/IOs. An X-decoder XDEC may also be referred to as a word line decoder or a row decoder. The X-decoder XDEC may receive a row address ADDR_R from the PIM controller 500 and may decode the row address ADDR_R to select and enable one of the rows (i.e., word lines) coupled to the selected memory bank. Each of the Y-decoders/IO circuits YDEC/IOs may include a Y-decoder YDEC and an I/O circuit IO. The Y-decoder YDEC may also be referred to as a bit line decoder or a column decoder. The Y-decoder YDEC may receive a column address ADD_C from the PIM controller 500 and may decode the column address ADD_C to select and enable at least one of the columns (i.e., bit lines) coupled to the selected memory bank. Each of the I/O circuits may include an I/O sense amplifier for sensing and amplifying a level of a read datum that is output from the corresponding memory bank during a read operation for the memory bank 411. In addition, the I/O circuit may include a write driver for driving a write datum during a write operation for the memory bank 411.

The MAC operator 420 of the PIM device 400 may have mostly the same configuration as the MAC operator 120 described with reference to FIG. 4. That is, the MAC operator 420 may be configured to include the data input circuit 121, the MAC circuit 122, and the data output circuit 123, as described with reference to FIG. 4. The data input circuit 121 may be configured to include the first input latch 121-1 and the second input latch 121-2. The MAC circuit 122 may be configured to include the multiplication logic circuit 122-1 and the addition logic circuit 122-2. The data output circuit 123 may be configured to include the output latch 123-1, the transfer gate 123-2, the delay circuit 123-3, and the inverter 123-4. In an embodiment, the first input latch 121-1, the second input latch 121-2, and the output latch 123-1 may be realized using flip-flops.

The MAC operator 420 may be different from the MAC operator 120 in that a MAC input latch signal MAC_L1 is simultaneously input to both of clock terminals of the first and second input latches 121-1 and 121-2. As indicated in the following descriptions, the weight data and the vector data may be simultaneously transmitted to the MAC operator 420 of the PIM device 400 included in the PIM system 1-2 according to the present embodiment. That is, the first data DA1 (i.e., the weight data) and the second data DA2 (i.e., the vector data) may be simultaneously input to both of the first input latch 121-1 and the second input latch 121-2 constituting the data input circuit 121, respectively. Accordingly, it may be unnecessary to apply an extra control signal to the clock terminals of the first and second input latches 121-1 and 121-2, and thus the MAC input latch signal MAC_L1 may be simultaneously input to both of the clock terminals of the first and second input latches 121-1 and 121-2 included in the MAC operator 420.

In another embodiment, the MAC operator 420 may be realized to have the same configuration as the MAC operator 120-1 described with reference to FIG. 16 to perform the operation illustrated in FIG. 14. Even in such a case, the MAC operator 420 may have the same configuration as described with reference to FIG. 16 except that the MAC input latch signal MAC_L1 is simultaneously input to both of the clock terminals of the first and second input latches 121-1 and 121-2 constituting the data input circuit 121. In yet another embodiment, the MAC operator 420 may be realized to have the same configuration as the MAC operator 120-2 described with reference to FIG. 19 to perform the operation illustrated in FIG. 17. Even in such a case, the MAC operator 420 may have the same configuration as described with reference to FIG. 19 except that the MAC input latch signal MAC_L1 is simultaneously input to both of the clock terminals of the first and second input latches 121-1 and 121-2 constituting the data input circuit 121.

The interface 431 of the PIM device 400 may receive the memory command M_CMD, the MAC commands MAC_CMDs, the bank selection signal BS, and the row/column addresses ADDR_R/ADDR_C from the PIM controller 500. The interface 431 may output the memory command M_CMD, together with the bank selection signal BS and the row/column addresses ADDR_R/ADDR_C, to the memory bank 411. The interface 431 may output the MAC commands MAC_CMDs to the memory bank 411 and the MAC operator 420. In such a case, the interface 431 may output the bank selection signal BS and the row/column addresses ADDR_R/ADDR_C to the memory bank 411. The data I/O pad 432 of the PIM device 400 may function as a data communication terminal between a device external to the PIM device 400, the global buffer 412, and the MAC unit (which includes the memory bank 411 and the MAC operator 420) included in the PIM device 400. The external device to the PIM device 400 may correspond to the PIM controller 500 of the PIM system 1-2 or a host located outside the PIM system 1-2. Accordingly, data that is output from the host or the PIM controller 500 may be input into the PIM device 400 through the data I/O pad 432. In addition, data generated by the PIM device 400 may be transmitted to the external device to the PIM device 400 through the data I/O pad 432.

The PIM controller 500 may control operations of the PIM device 400. In an embodiment, the PIM controller 500 may control the PIM device 400 such that the PIM device 400 operates in the memory mode or the MAC mode. In the event that the PIM controller 500 controls the PIM device 500 such that the PIM device 400 operates in the memory mode, the PIM device 400 may perform a data read operation or a data write operation for the memory bank 411. In the event that the PIM controller 500 controls the PIM device 400 such that the PIM device 400 operates in the MAC mode, the PIM device 400 may perform the MAC arithmetic operation for the MAC operator 420. In the event that the PIM controller 500 controls the PIM device 400 such that the PIM device 400 operates in the MAC mode, the PIM device 400 may also perform the data read operation and the data write operation for the memory bank 411 and the global buffer 412 to execute the MAC arithmetic operation.

The PIM controller 500 may be configured to include the command queue logic 210, the scheduler 220, the memory command generator 230, a MAC command generator 540, and an address generator 550. The scheduler 220 may include the mode selector 221. The command queue logic 210 may receive the request REQ from an external device (e.g., a host of the PIM system 1-2) and store a command queue corresponding the request REQ in the command queue logic 210. The command queue stored in the command queue logic 210 may be transmitted to the memory command generator 230 or the MAC command generator 540 according to a sequence determined by the scheduler 220. The scheduler 220 may adjust a timing of the command queue when the command queue stored in the command queue logic 210 is output from the command queue logic 210. The scheduler 210 may include the mode selector 221 that generates a mode selection signal including information on whether command queue stored in the command queue logic 210 relates to the memory mode or the MAC mode. The memory command generator 230 may receive the command queue related to the memory mode of the PIM device 400 from the command queue logic 210 to generate and output the memory command M_CMD. The command queue logic 210, the scheduler 220, the mode selector 221, and the memory command generator 230 may have the same function as described with reference to FIG. 2.

The MAC command generator 540 may receive the command queue related to the MAC mode of the PIM device 400 from the command queue logic 210. The MAC command generator 540 may decode the command queue to generate and output the MAC command signals MAC_CMDs. The MAC command signals MAC_CMDs output from the MAC command generator 540 may be transmitted to the PIM device 400. The data read operation for the memory bank 411 of the PIM device 400 may be performed by the MAC command signals MAC_CMDs that are output from the MAC command generator 540, and the MAC arithmetic operation of the MAC operator 420 may also be performed by the MAC command signals MAC_CMDs that are output from the MAC command generator 540. The MAC command signals MAC_CMDs and the MAC arithmetic operation of the PIM device 400 according to the MAC command signals MAC_CMDs will be described in detail with reference to FIG. 21.

The address generator 550 may receive address information from the command queue logic 210. The address generator 550 may generate the bank selection signal BS for selecting a memory bank where, for example, the memory bank 411 represents multiple memory banks. The address generator 550 may transmit the bank selection signal BS to the PIM device 400. In addition, the address generator 550 may generate the row address ADDR_R and the column address ADDR_C for accessing a region (e.g., memory cells) in the memory bank 411 and may transmit the row address ADDR_R and the column address ADDR_C to the PIM device 400.

FIG. 21 illustrates the MAC command signals MAC_CMDs that are output from the MAC command generator 540 included in the PIM system 1-2 according to the second embodiment of the present disclosure. As illustrated in FIG. 21, the MAC command signals MAC_CMDs may include first to fourth MAC command signals. In an embodiment, the first MAC command signal may be a MAC read signal MAC_RD_BK, the second MAC command signal may be a MAC input latch signal MAC_L1, the third MAC command signal may be a MAC output latch signal MAC_L3, and the fourth MAC command signal may be a MAC latch reset signal MAC_L_RST.

The MAC read signal MAC_RD_BK may control an operation for reading the first data (e.g., the weight data) out of the memory bank 411 to transmit the first data to the MAC operator 420. The MAC input latch signal MAC_L1 may control an input latch operation of the weight data transmitted from the first memory bank 411 to the MAC operator 420. The MAC output latch signal MAC_L3 may control an output latch operation of the MAC result data generated by the MAC operator 420. And, the MAC latch reset signal MAC_L_RST may control an output operation of the MAC result data generated by the MAC operator 420 and a reset operation of an output latch included in the MAC operator 420.

The PIM system 1-2 according to the present embodiment may also be configured to perform the deterministic MAC arithmetic operation. Thus, the MAC command signals MAC_CMDs transmitted from the PIM controller 500 to the PIM device 400 may be sequentially generated with fixed time intervals. Accordingly, the PIM controller 500 does not require any extra end signals of various operations executed for the MAC arithmetic operation to generate the MAC command signals MAC_CMDs for controlling the MAC arithmetic operation. In an embodiment, latencies of the various operations executed by MAC command signals MAC_CMDs for controlling the MAC arithmetic operation may be set to have fixed values in order to perform the deterministic MAC arithmetic operation. In such a case, the MAC command signals MAC_CMDs may be sequentially output from the PIM controller 500 with fixed time intervals corresponding to the fixed latencies.

FIG. 22 is a flowchart illustrating processes of the MAC arithmetic operation described with reference to FIG. 5, which are performed in the PIM system 1-2 according to the second embodiment of the present disclosure. In addition, FIGS. 23 to 26 are block diagrams illustrating the processes of the MAC arithmetic operation illustrated in FIG. 5, which are performed in the PIM system 1-2 according to the second embodiment of the present disclosure. Referring to FIGS. 22 to 26, the first data (i.e., the weight data) may be written into the memory bank 411 at a step 361 to perform the MAC arithmetic operation. Thus, the weight data may be stored in the memory bank 411 of the PIM device 400. In the present embodiment, it may be assumed that the weight data are the elements W0.0, . . . , and W7.7 constituting the weight matrix of FIG. 5.

At a step 362, whether an inference is requested may be determined. An inference request signal may be transmitted from an external device located outside of the PIM system 1-2 to the PIM controller 500 of the PIM system 1-2. In an embodiment, if no inference request signal is transmitted to the PIM controller 500, the PIM system 1-2 may be in a standby mode until the inference request signal is transmitted to the PIM controller 500. Alternatively, if no inference request signal is transmitted to the PIM controller 500, the PIM system 1-2 may perform operations (e.g., data read/write operations) other than the MAC arithmetic operation in the memory mode until the inference request signal is transmitted to the PIM controller 500. In the present embodiment, it may be assumed that the second data (i.e., the vector data) are transmitted together with the inference request signal. In addition, it may be assumed that the vector data are the elements X0.0, . . . , and X7.0 constituting the vector matrix of FIG. 5. If the inference request signal is transmitted to the PIM controller 500 at the step 362, then the PIM controller 500 may write the vector data transmitted with the inference request signal into the global buffer 412 at a step 363. Accordingly, the vector data may be stored in the global buffer 412 of the PIM device 400.

At a step 364, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC read signal MAC_RD_BK to the PIM device 400, as illustrated in FIG. 23. In such a case, the address generator 550 of the PIM controller 500 may generate and transmit the row/column address ADDR_R/ADDR_C to the PIM device 400. Although not shown in the drawings, if a plurality of memory banks are disposed in the PIM device 400, the address generator 550 may transmit a bank selection signal for selecting the memory bank 411 among the plurality of memory banks as well as the row/column address ADDR_R/ADDR_C to the PIM device 400. The MAC read signal MAC_RD_BK that is input to the PIM device 400 may control the data read operation for the memory bank 411 of the PIM device 400. The memory bank 411 may output and transmit the elements W0.0, . . . , and W0.7 in the first row of the weight matrix of the weight data stored in a region of the memory bank 411, which is designated by the row/column address ADDR_R/ADDR_C, to the MAC operator 420 in response to the MAC read signal MAC_RD_BK. In an embodiment, the data transmission from the memory bank 411 to the MAC operator 420 may be executed through a BIO line which is provided specifically for data transmission between the memory bank 411 and the MAC operator 420.

Meanwhile, the vector data X0.0, . . . , and X7.0 stored in the global buffer 412 may also be transmitted to the MAC operator 420 in synchronization with a point in time when the weight data are transmitted from the memory bank 411 to the MAC operator 420. In order to transmit the vector data X0.0, . . . , and X7.0 from the global buffer 412 to the MAC operator 420, a control signal for controlling the read operation for the global buffer 412 may be generated in synchronization with the MAC read signal MAC_RD_BK that is output from the MAC command generator 540 of the PIM controller 500. The data transmission between the global buffer 412 and the MAC operator 420 may be executed through a GIO line. Thus, the weight data and the vector data may be independently transmitted to the MAC operator 420 through two separate transmission lines, respectively. In an embodiment, the weight data and the vector data may be simultaneously transmitted to the MAC operator 420 through the BIO line and the GIO line, respectively.

At a step 365, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC input latch signal MAC_L1 to the PIM device 400, as illustrated in FIG. 24. The MAC input latch signal MAC_L1 may control the input latch operation of the weight data and the vector data for the MAC operator 420 of the PIM device 400. The elements W0.0, . . . , and W0.7 in the first row of the weight matrix and the elements X0.0, . . . , and X7.0 in the first column of the vector matrix may be input to the MAC circuit 122 of the MAC operator 420 by the input latch operation. The MAC circuit 122 may include the plurality of multipliers (e.g., the eight multipliers 122-11), the number of which is equal to the number of columns of the weight matrix and the number of rows of the vector matrix. The elements W0.0, . . . , and W0.7 in the first row of the weight matrix may be input to the first to eighth multipliers 122-11, respectively, and the elements X0.0, . . . , and X7.0 in the first column of the vector matrix may also be input to the first to eighth multipliers 122-11, respectively.

At a step 366, the MAC circuit 122 of the MAC operator 420 may perform the MAC arithmetic operation of an R^(th) row of the weight matrix and the first column of the vector matrix, which are input to the MAC circuit 122. An initial value of ‘R’ may be set as ‘1’. Thus, the MAC arithmetic operation of the first row of the weight matrix and the first column of the vector matrix may be performed a first time. Specifically, as described with reference to FIG. 4, each of the multipliers 122-11 of the multiplication logic circuit 122-1 may perform a multiplying calculation of the inputted data, and the result data of the multiplying calculation may be input to the addition logic circuit 122-2. The addition logic circuit 122-2 may receive output data from the multipliers 122-11 and may perform the adding calculation of the output data of the multipliers 122-11 to output the result data of the adding calculation. The output data of the addition logic circuit 122-2 may correspond to result data (i.e., MAC result data) of the MAC arithmetic operation of the first row included in the weight matrix and the column included in the vector matrix. Thus, the output data of the addition logic circuit 122-2 may correspond to the element MAC0.0 located at the first row of the ‘8×1’ MAC result matrix with the eight elements of MAC0.0, . . . , and MAC7.0 illustrated in FIG. 5. The output data MAC0.0 of the addition logic circuit 122-2 may be input to the output latch 123-1 disposed in the data output circuit 123 of the MAC operator 420, as described with reference to FIG. 4.

At a step 367, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC output latch signal MAC_L3 to the PIM device 400, as illustrated in FIG. 25. The MAC output latch signal MAC_L3 may control the output latch operation of the MAC result data MAC0.0 performed by the MAC operator 420 of the PIM device 400. The MAC result data MAC0.0 transmitted from the MAC circuit 122 of the MAC operator 420 to the output latch 123-1 may be output from the output latch 123-1 by the output latch operation performed in synchronization with the MAC output latch signal MAC_L3, as described with reference to FIG. 4. The MAC result data MAC0.0 that is output from the output latch 123-1 may be input to the transfer gate 123-2 of the data output circuit 123.

At a step 368, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC latch reset signal MAC_L_RST to the PIM device 400, as illustrated in FIG. 26. The MAC latch reset signal MAC_L_RST may control an output operation of the MAC result data MAC0.0 generated by the MAC operator 420 and a reset operation of the output latch 123-1 included in the MAC operator 420. As described with reference to FIG. 4, the transfer gate 123-2 receiving the MAC result data MAC0.0 from the output latch 123-1 of the MAC operator 420 may be synchronized with the MAC latch reset signal MAC_L_RST to output the MAC result data MAC0.0. In an embodiment, the MAC result data MAC0.0 that is output from the MAC operator 420 may be stored into the memory bank 411 through the BIO line in the PIM device 400.

At a step 369, the row number ‘R’ of the weight matrix for which the MAC arithmetic operation is performed may be increased by ‘1’. Because the MAC arithmetic operation for the first row among the first to eight rows of the weight matrix has been performed during the previous steps, the row number of the weight matrix may change from ‘1’ to ‘2’ at the step 369. At a step 370, whether the row number changed at the step 369 is greater than the row number of the last row (i.e., the eighth row) of the weight matrix may be determined. Because the row number of the weight matrix is changed to ‘2’ at the step 370, a process of the MAC arithmetic operation may be fed back to the step 364.

If the process of the MAC arithmetic operation is fed back to the step 364 from the step 370, the same processes as described with reference to the steps 364 to 370 may be executed again for the increased row number of the weight matrix. That is, as the row number of the weight matrix changes from ‘1’ to ‘2’, the MAC arithmetic operation may be performed for the second row of the weight matrix instead of the first row of the weight matrix with the vector matrix. If the process of the MAC arithmetic operation is fed back to the step 364 from the step 370, the processes from the step 364 to the step 370 may be iteratively performed until the MAC arithmetic operation is performed for all of the rows of the weight matrix with the vector matrix. If the MAC arithmetic operation for the eighth row of the weight matrix terminates and the row number of the weight matrix changes from ‘8’ to ‘9’ at the step 369, the MAC arithmetic operation may terminate because the row number of ‘9’ is greater than the last row number of ‘8’ at the step 370.

FIG. 27 is a flowchart illustrating processes of the MAC arithmetic operation described with reference to FIG. 14, which are performed in the PIM system 1-2 according to the second embodiment of the present disclosure. In order to perform the MAC arithmetic operation according to the present embodiment, the MAC operator 420 of the PIM device 400 may have the same configuration as the MAC operator 120-1 illustrated in FIG. 16. Referring to FIGS. 20 and 27, the first data (i.e., the weight data) may be written into the memory bank 411 at a step 381 to perform the MAC arithmetic operation. Thus, the weight data may be stored in the memory bank 411 of the PIM device 400. In the present embodiment, it may be assumed that the weight data are the elements W0.0, . . . , and W7.7 constituting the weight matrix of FIG. 14.

At a step 382, whether an inference is requested may be determined. An inference request signal may be transmitted from an external device located outside of the PIM system 1-2 to the PIM controller 500 of the PIM system 1-2. In an embodiment, if no inference request signal is transmitted to the PIM controller 500, the PIM system 1-2 may be in a standby mode until the inference request signal is transmitted to the PIM controller 500. Alternatively, if no inference request signal is transmitted to the PIM controller 500, the PIM system 1-2 may perform operations (e.g., data read/write operations) other than the MAC arithmetic operation in the memory mode until the inference request signal is transmitted to the PIM controller 500. In the present embodiment, it may be assumed that the second data (i.e., the vector data) are transmitted together with the inference request signal. In addition, it may be assumed that the vector data are the elements X0.0, . . . , and X7.0 constituting the vector matrix of FIG. 14. If the inference request signal is transmitted to the PIM controller 500 at the step 382, then the PIM controller 500 may write the vector data transmitted with the inference request signal into the global buffer 412 at a step 383. Accordingly, the vector data may be stored in the global buffer 412 of the PIM device 400.

At a step 384, an output latch of a MAC operator 420 may be initially set to have bias data and the initially set bias data may be fed back to an accumulative adder of the MAC operator 420. This process is executed to perform the matrix adding calculation of the MAC result matrix and the bias matrix, which is described with reference to FIG. 14. That is, as illustrated in FIG. 16, the output latch 123-1 of the data output circuit 123-A included in the MAC operator 420 may be initially set to have the bias data of the bias matrix. Because the matrix multiplying calculation is executed for the first row of the weight matrix, the element B0.0 located at first row of the bias matrix may be initially set as the bias data in the output latch 123-1. The output latch 123-1 may output the bias data B0.0, and the bias data B0.0 that is output from the output latch 123-1 may be input to the accumulative adder 122-21D of the addition logic circuit 122-2 included in the MAC operator 420.

In an embodiment, in order to output the bias data B0.0 out of the output latch 123-1 and to feed back the bias data B0.0 to the accumulative adder 122-21D, the MAC command generator 540 of the PIM controller 500 may transmit the MAC output latch signal MAC_L3 to the MAC operator 420 of the PIM device 400. When a subsequent MAC arithmetic operation is performed, the accumulative adder 122-21D of the MAC operator 420 may add the MAC result data MAC0.0 that is output from the adder 122-21C disposed at the last stage to the bias data B0.0 which is fed back from the output latch 123-1 to generate the biased result data Y0.0 and may output the biased result data Y0.0 to the output latch 123-1. The biased result data Y0.0 may be output from the output latch 123-1 in synchronization with the MAC output latch signal MAC_L3 transmitted in a subsequent process.

At a step 385, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC read signal MAC_RD_BK to the PIM device 400, as illustrated in FIG. 23. In such a case, the address generator 550 of the PIM controller 500 may generate and transmit the row/column address ADDR_R/ADDR_C to the PIM device 400. The MAC read signal MAC_RD_BK that is input to the PIM device 400 may control the data read operation for the memory bank 411 of the PIM device 400. The memory bank 411 may output and transmit the elements W0.0, . . . , and W0.7 in the first row of the weight matrix of the weight data stored in a region of the memory bank 411, which is designated by the row/column address ADDR_R/ADDR_C, to the MAC operator 420 in response to the MAC read signal MAC_RD_BK. In an embodiment, the data transmission from the memory bank 411 to the MAC operator 420 may be executed through a BIO line which is provided specifically for data transmission between the memory bank 411 and the MAC operator 420.

Meanwhile, the vector data X0.0, . . . , and X7.0 stored in the global buffer 412 may also be transmitted to the MAC operator 420 in synchronization with a point in time when the weight data are transmitted from the memory bank 411 to the MAC operator 420. In order to transmit the vector data X0.0, . . . , and X7.0 from the global buffer 412 to the MAC operator 420, a control signal for controlling the read operation for the global buffer 412 may be generated in synchronization with the MAC read signal MAC_RD_BK that is output from the MAC command generator 540 of the PIM controller 500. The data transmission between the global buffer 412 and the MAC operator 420 may be executed through a GIO line. Thus, the weight data and the vector data may be independently transmitted to the MAC operator 420 through two separate transmission lines, respectively. In an embodiment, the weight data and the vector data may be simultaneously transmitted to the MAC operator 420 through the BIO line and the GIO line, respectively.

At a step 386, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC input latch signal MAC_L1 to the PIM device 400, as illustrated in FIG. 24. The MAC input latch signal MAC_L1 may control the input latch operation of the weight data and the vector data for the MAC operator 420 of the PIM device 400. The elements W0.0, . . . , and W0.7 in the first row of the weight matrix and the elements X0.0, . . . , and X7.0 in the first column of the vector matrix may be input to the MAC circuit 122 of the MAC operator 420 by the input latch operation. The MAC circuit 122 may include the plurality of multipliers (e.g., the eight multipliers 122-11), the number of which is equal to the number of columns of the weight matrix and the number of rows of the vector matrix. The elements W0.0, . . . , and W0.7 in the first row of the weight matrix may be input to the first to eighth multipliers 122-11, respectively, and the elements X0.0, . . . , and X7.0 in the first column of the vector matrix may also be input to the first to eighth multipliers 122-11, respectively.

At a step 387, the MAC circuit 122 of the MAC operator 420 may perform the MAC arithmetic operation of an R^(th) row of the weight matrix and the first column of the vector matrix, which are input to the MAC circuit 122. An initial value of ‘R’ may be set as ‘1’. Thus, the MAC arithmetic operation of the first row of the weight matrix and the first column of the vector matrix may be performed a first time. Specifically, each of the multipliers 122-11 of the multiplication logic circuit 122-1 may perform a multiplying calculation of the inputted data, and the result data of the multiplying calculation may be input to the addition logic circuit 122-2. The addition logic circuit 122-2 may receive output data of the multipliers 122-11 and may perform the adding calculation of the output data of the multipliers 122-11 to output the result data of the adding calculation to the accumulative adder 122-21D. The output data of the adder 122-21C included in the addition logic circuit 122-2 may correspond to result data (i.e., MAC result data) of the MAC arithmetic operation of the first row included in the weight matrix and the column included in the vector matrix. The accumulative adder 122-21D may add the output data MAC0.0 of the adder 122-21C to the bias data 130.0 fed back from the output latch 123-1 and may output the result data of the adding calculation. The output data (i.e., the biased result data Y0.0) of the accumulative adder 122-21D may be input to the output latch 123-1 disposed in the data output circuit 123-A of the MAC operator 420.

At a step 388, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC output latch signal MAC_L3 to the PIM device 400, as described with reference to FIG. 25. The MAC output latch signal MAC_L3 may control the output latch operation for the output latch 123-1 of the MAC operator 420 included in the PIM device 400. The output latch 123-1 of the MAC operator 420 may output the biased result data Y0.0 according to the output latch operation performed in synchronization with the MAC output latch signal MAC_L3. The biased result data Y0.0 that is output from the output latch 123-1 may be input to the transfer gate 123-2 of the data output circuit 123-A.

At a step 389, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC latch reset signal MAC_L_RST to the PIM device 400, as illustrated in FIG. 26. The MAC latch reset signal MAC_L_RST may control an output operation of the biased result data Y0.0 generated by the MAC operator 420 and a reset operation of the output latch 123-1 included in the MAC operator 420. The transfer gate 123-2 receiving the biased result data Y0.0 from the output latch 123-1 of the MAC operator 420 may be synchronized with the MAC latch reset signal MAC_L_RST to output the biased result data Y0.0. In an embodiment, the biased result data Y0.0 that is output from the MAC operator 120 may be stored into the memory bank 411 through the BIO line in the PIM device 400.

At a step 390, the row number ‘R’ of the weight matrix for which the MAC arithmetic operation is performed may be increased by ‘1’. Because the MAC arithmetic operation for the first row among the first to eight rows of the weight matrix has been performed at the previous steps, the row number of the weight matrix may change from ‘1’ to ‘2’ at the step 390. At a step 391, whether the row number changed at the step 390 is greater than the row number of the last row (i.e., the eighth row) of the weight matrix may be determined. Because the row number of the weight matrix is changed to ‘2’ at the step 390, a process of the MAC arithmetic operation may be fed back to the step 384.

If the process of the MAC arithmetic operation is fed back to the step 384 at the step 391, the same processes as described with reference to the steps 384 to 391 may be executed again for the increased row number of the weight matrix. That is, as the row number of the weight matrix changes from ‘1’ to ‘2’, the MAC arithmetic operation may be performed for the second row of the weight matrix instead of the first row of the weight matrix with the vector matrix. If the process of the MAC arithmetic operation is fed back to the step 384 at the step 391, then the processes from the step 384 to the step 390 may be iteratively performed until the MAC arithmetic operation is performed for all of the rows of the weight matrix with the vector matrix. If the MAC arithmetic operation for the eighth row of the weight matrix terminates and the row number of the weight matrix changes from ‘8’ to ‘9’ at the step 390, then the MAC arithmetic operation may terminate because the row number of ‘9’ is greater than the last row number of ‘8’ at the step 391.

FIG. 28 is a flowchart illustrating processes of the MAC arithmetic operation described with reference to FIG. 17, which are performed in the PIM system 1-2 according to the second embodiment of the present disclosure. In order to perform the MAC arithmetic operation according to the present embodiment, the MAC operator 420 of the PIM device 400 may have the same configuration as the MAC operator 120-2 illustrated in FIG. 19. Referring to FIGS. 19 and 28, the first data (i.e., the weight data) may be written into the memory bank 411 at a step 601 to perform the MAC arithmetic operation. Thus, the weight data may be stored in the memory bank 411 of the PIM device 400. In the present embodiment, it may be assumed that the weight data are the elements W0.0, . . . , and W7.7 constituting the weight matrix of FIG. 17.

At a step 602, whether an inference is requested may be determined. An inference request signal may be transmitted from an external device located outside of the PIM system 1-2 to the PIM controller 500 of the PIM system 1-2. In an embodiment, if no inference request signal is transmitted to the PIM controller 500, the PIM system 1-2 may be in a standby mode until the inference request signal is transmitted to the PIM controller 500. Alternatively, if no inference request signal is transmitted to the PIM controller 500, the PIM system 1-2 may perform operations (e.g., data read/write operations) other than the MAC arithmetic operation in the memory mode until the inference request signal is transmitted to the PIM controller 500. In the present embodiment, it may be assumed that the second data (i.e., the vector data) are transmitted together with the inference request signal. In addition, it may be assumed that the vector data are the elements X0.0, . . . , and X7.0 constituting the vector matrix of FIG. 17. If the inference request signal is transmitted to the PIM controller 500 at the step 602, then the PIM controller 500 may write the vector data transmitted with the inference request signal into the global buffer 412 at a step 603. Accordingly, the vector data may be stored in the global buffer 412 of the PIM device 400.

At a step 604, an output latch of a MAC operator 420 may be initially set to have bias data and the initially set bias data may be fed back to an accumulative adder of the MAC operator 420. This process is executed to perform the matrix adding calculation of the MAC result matrix and the bias matrix, which is described with reference to FIG. 17. That is, as described with reference to FIG. 19, the output latch 123-1 of the data output circuit 123-B included in the MAC operator 420 may be initially set to have the bias data of the bias matrix. Because the matrix multiplying calculation is executed for the first row of the weight matrix, the element B0.0 located at first row of the bias matrix may be initially set as the bias data in the output latch 123-1. The output latch 123-1 may output the bias data B0.0, and the bias data B0.0 that is output from the output latch 123-1 may be input to the accumulative adder 122-21D of the addition logic circuit 122-2 included in the MAC operator 420.

In an embodiment, in order to output the bias data B0.0 out of the output latch 123-1 and to feed back the bias data B0.0 to the accumulative adder 122-21D, the MAC command generator 540 of the PIM controller 500 may transmit the MAC output latch signal MAC_L3 to the MAC operator 420 of the PIM device 400. When a subsequent MAC arithmetic operation is performed, the accumulative adder 122-21D of the MAC operator 420 may add the MAC result data MAC0.0 that is output from the adder 122-21C disposed at the last stage of the addition logic circuit 122-2 to the bias data B0.0 which is fed back from the output latch 123-1 to generate the biased result data Y0.0 and may output the biased result data Y0.0 to the output latch 123-1. The biased result data Y0.0 may be output from the output latch 123-1 in synchronization with the MAC output latch signal MAC_L3 transmitted in a subsequent process.

At a step 605, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC read signal MAC_RD_BK to the PIM device 400, as illustrated in FIG. 23. In such a case, the address generator 550 of the PIM controller 500 may generate and transmit the row/column address ADDR_R/ADDR_C to the PIM device 400. The MAC read signal MAC_RD_BK that is input to the PIM device 400 may control the data read operation for the memory bank 411 of the PIM device 400. The memory bank 411 may output and transmit the elements W0.0, . . . , and W0.7 in the first row of the weight matrix of the weight data stored in a region of the memory bank 411, which is designated by the row/column address ADDR_R/ADDR_C, to the MAC operator 420 in response to the MAC read signal MAC_RD_BK. In an embodiment, the data transmission from the memory bank 411 to the MAC operator 420 may be executed through a BIO line which is provided specifically for data transmission between the memory bank 411 and the MAC operator 420.

Meanwhile, the vector data X0.0, . . . , and X7.0 stored in the global buffer 412 may also be transmitted to the MAC operator 420 in synchronization with a point in time when the weight data are transmitted from the memory bank 411 to the MAC operator 420. In order to transmit the vector data X0.0, . . . , and X7.0 from the global buffer 412 to the MAC operator 420, a control signal for controlling the read operation for the global buffer 412 may be generated in synchronization with the MAC read signal MAC_RD_BK that is output from the MAC command generator 540 of the PIM controller 500. The data transmission between the global buffer 412 and the MAC operator 420 may be executed through a GIO line. Thus, the weight data and the vector data may be independently transmitted to the MAC operator 420 through two separate transmission lines, respectively. In an embodiment, the weight data and the vector data may be simultaneously transmitted to the MAC operator 420 through the BIO line and the GIO line, respectively.

At a step 606, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC input latch signal MAC_L1 to the PIM device 400, as described with reference to FIG. 24. The MAC input latch signal MAC_L1 may control the input latch operation of the weight data and the vector data for the MAC operator 420 of the PIM device 400. The elements W0.0, . . . , and W0.7 in the first row of the weight matrix and the elements X0.0, . . . , and X7.0 in the first column of the vector matrix may be input to the MAC circuit 122 of the MAC operator 420 by the input latch operation. The MAC circuit 122 may include the plurality of multipliers (e.g., the eight multipliers 122-11), the number of which is equal to the number of columns of the weight matrix and the number of rows of the vector matrix. The elements W0.0, . . . , and W0.7 in the first row of the weight matrix may be input to the first to eighth multipliers 122-11, respectively, and the elements X0.0, . . . , and X7.0 in the first column of the vector matrix may also be input to the first to eighth multipliers 122-11, respectively.

At a step 607, the MAC circuit 122 of the MAC operator 420 may perform the MAC arithmetic operation of an R^(th) row of the weight matrix and the first column of the vector matrix, which are input to the MAC circuit 122. An initial value of ‘R’ may be set as ‘1’. Thus, the MAC arithmetic operation of the first row of the weight matrix and the first column of the vector matrix may be performed a first time. Specifically, each of the multipliers 122-11 of the multiplication logic circuit 122-1 may perform a multiplying calculation of the inputted data, and the result data of the multiplying calculation may be input to the addition logic circuit 122-2. The addition logic circuit 122-2 may receive output data of the multipliers 122-11 and may perform the adding calculation of the output data of the multipliers 122-11 to output the result data of the adding calculation to the accumulative adder 122-21D. The output data of the adder 122-21C included in the addition logic circuit 122-2 may correspond to result data (i.e., the MAC result data MAC0.0) of the MAC arithmetic operation of the first row included in the weight matrix and the column included in the vector matrix. The accumulative adder 122-21D may add the output data MAC0.0 of the adder 122-21C to the bias data B0.0 fed back from the output latch 123-1 and may output the result data of the adding calculation. The output data (i.e., the biased result data Y0.0) of the accumulative adder 122-21D may be input to the output latch 123-1 disposed in the data output circuit 123-A of the MAC operator 420.

At a step 608, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC output latch signal MAC_L3 to the PIM device 400, as described with reference to FIG. 25. The MAC output latch signal MAC_L3 may control the output latch operation for the output latch 123-1 of the MAC operator 420 included in the PIM device 400. The output latch 123-1 of the MAC operator 420 may output the biased result data Y0.0 according to the output latch operation performed in synchronization with the MAC output latch signal MAC_L3. The biased result data Y0.0 that is output from the output latch 123-1 may be input to the activation function logic circuit 123-5, which is illustrated in FIG. 19. At a step 610, the activation function logic circuit 123-5 may apply an activation function to the biased result data Y0.0 to generate a final output value, and the final output value may be input to the transfer gate (123-2 of FIG. 4).

At a step 610, the MAC command generator 540 of the PIM controller 500 may generate and transmit the MAC latch reset signal MAC_L_RST to the PIM device 400, as described with reference to FIG. 26. The MAC latch reset signal MAC_L_RST may control an output operation of the final output value generated by the MAC operator 420 and a reset operation of the output latch 123-1 included in the MAC operator 420. The transfer gate 123-2 receiving the final output value from the activation function logic circuit 123-5 of the data output circuit 123-B included in the MAC operator 420 may be synchronized with the MAC latch reset signal MAC_L_RST to output the final output value. In an embodiment, the final output value that is output from the MAC operator 420 may be stored into the memory bank 411 through the BIO line in the PIM device 400.

At a step 611, the row number ‘R’ of the weight matrix for which the MAC arithmetic operation is performed may be increased by ‘1’. Because the MAC arithmetic operation for the first row among the first to eight rows of the weight matrix has been performed at the previous steps, the row number of the weight matrix may change from ‘1’ to ‘2’ at the step 611. At a step 612, whether the row number changed at the step 611 is greater than the row number of the last row (i.e., the eighth row) of the weight matrix may be determined. Because the row number of the weight matrix is changed to ‘2’ at the step 611, a process of the MAC arithmetic operation may be fed back to the step 604.

If the process of the MAC arithmetic operation is fed back to the step 604 from the step 612, the same processes as described with reference to the steps 604 to 612 may be executed again for the increased row number of the weight matrix. That is, as the row number of the weight matrix changes from ‘1’ to ‘2’, the MAC arithmetic operation may be performed for the second row of the weight matrix instead of the first row of the weight matrix with the vector matrix to generate the MAC result data (corresponding to the element MAC1.0 located in the second row of the MAC result matrix) and the bias data (corresponding to the element B1.0 located in the second row of the bias matrix). If the process of the MAC arithmetic operation is fed back to the step 604 from the step 612, the processes from the step 604 to the step 612 may be iteratively performed until the MAC arithmetic operation is performed for all of the rows (i.e., first to eighth rows) of the weight matrix with the vector matrix. If the MAC arithmetic operation for the eighth row of the weight matrix terminates and the row number of the weight matrix changes from ‘8’ to ‘9’ at the step 611, the MAC arithmetic operation may terminate because the row number of ‘9’ is greater than the last row number of ‘8’ at the step 612.

FIG. 29 is a block diagram illustrating a PIM system 1-3 according to a third embodiment of the present disclosure. As illustrated in FIG. 29, the PIM system 1-3 may have substantially the same configuration as the PIM system 1-1 illustrated in FIG. 2 except that a PIM controller 200A of the PIM system 1-3 further includes a mode register set (MRS) 260 as compared with the PIM controller 200 of the PIM system 1-1. Thus, the same explanation as described with reference to FIG. 2 will be omitted hereinafter. The mode register set 260 in the PIM controller 200A may receive an MRS signal instructing arrangement of various signals necessary for the MAC arithmetic operation of the PIM system 1-3. In an embodiment, the mode register set 260 may receive the MRS signal from the mode selector 221 included in the scheduler 220. However, in another embodiment, the MRS signal may be provided by an extra logic circuit other than the mode selector 221. The mode register set 260 receiving the MRS signal may transmit the MRS signal to the MAC command generator 240. For an embodiment, the MRS 260 represents a MRS circuit.

In an embodiment, the MRS signal may include timing information on when the MAC command signals MAC_CMDs are generated. In such a case, the deterministic operation of the PIM system 1-3 may be performed by the MRS signal provided by the MRS 260. In another embodiment, the MRS signal may include information on the timing related to an interval between the MAC modes or information on a mode change between the MAC mode and the memory mode. In an embodiment, generation of the MRS signal in the MRS 260 may be executed before the vector data are stored in the second memory bank 112 of the PIM device 100 by the inference request signal transmitted from an external device to the PIM controller 200A. Alternatively, the generation of the MRS signal in the MRS 260 may be executed after the vector data are stored in the second memory bank 112 of the PIM device 100 by the inference request signal transmitted from an external device to the PIM controller 200A.

FIG. 30 is a block diagram illustrating a PIM system 1-4 according to a fourth embodiment of the present disclosure. As illustrated in FIG. 30, the PIM system 1-4 may have substantially the same configuration as the PIM system 1-2 illustrated in FIG. 20 except that a PIM controller 500A of the PIM system 1-4 further includes the mode register set (MRS) 260 as compared with the PIM controller 500 of the PIM system 1-2. Thus, the same explanation as described with reference to FIG. 20 will be omitted hereinafter. The mode register set 260 in the PIM controller 500A may receive an MRS signal instructing arrangement of various signals necessary for the MAC arithmetic operation of the PIM system 1-4. In an embodiment, the mode register set 260 may receive the MRS signal from the mode selector 221 included in the scheduler 220. However, in another embodiment, the MRS signal may be provided by an extra logic circuit other than the mode selector 221. The mode register set 260 receiving the MRS signal may transmit the MRS signal to the MAC command generator 540.

In an embodiment, the MRS signal may include timing information on when the MAC command signals MAC_CMDs are generated. In such a case, the deterministic operation of the PIM system 1-4 may be performed by the MRS signal provided by the MRS 260. In another embodiment, the MRS signal may include information on the timing related to an interval between the MAC modes or information on a mode change between the MAC mode and the memory mode. In an embodiment, generation of the MRS signal in the MRS 260 may be executed before the vector data are stored in the global buffer 412 of the PIM device 400 by the inference request signal transmitted from an external device to the PIM controller 500A. Alternatively, the generation of the MRS signal in the MRS 260 may be executed after the vector data are stored in the global buffer 412 of the PIM device 400 by the inference request signal transmitted from an external device to the PIM controller 500A.

FIG. 31 is a block diagram illustrating a MAC circuit 1000 according to an embodiment of the present disclosure. Referring to FIG. 31, the MAC circuit 1000 may include a multiplying circuit 1100 and an adding circuit 1200. The multiplying circuit 1100 may include a first multiplier 1110 and a second multiplier 1120. The adding circuit 1200 may include an adder 1210.

The multiplying circuit 1100 may receive first input data DA10+DA11 and second input data DA20+DA21. The first input data DA10+DA11 may be a binary stream with 2×N bits, and the second input data DA20+DA21 may be a binary stream with 2×M bits (where, “N” is a natural number which is equal to or greater than “1”, and “M” is a natural number which is equal to or greater than “1”). The first input data DA10+DA11 may be divided into two parts to provide first input data DA10 and first input data DA11 with the same number of bits, and the first input data DA10 and the first input data DA11 may be input to respective ones of the first multiplier 1110 and the second multiplier 1120. In an embodiment, the first input data DA10 may be configured to have “N”-number of low-order bits of the first input data DA10+DA11 with 2×N bits and may be input to the first multiplier 1110, and the first input data DA11 may be configured to have “N”-number of high-order bits of the first input data DA10+DA11 with 2×N bits and may be input to the second multiplier 1120. The second input data DA20+DA21 may also be divided into two parts to provide second input data DA20 and second input data DA21 with the same number of bits, and the second input data DA20 and the second input data DA21 may be input to respective ones of the first multiplier 1110 and the second multiplier 1120. In an embodiment, the second input data DA20 may be configured to have “M”-number of low-order bits of the second input data DA20+DA21 with 2×M bits and may be input to the first multiplier 1110, and the second input data DA21 may be configured to have “M”-number of high-order bits of the second input data DA20+DA21 with 2×M bits and may be input to the second multiplier 1120.

The first multiplier 1110 may perform a first multiplying calculation of the first input data DA10 with N bits and the second input data DA20 with M bits. The first multiplier 1110 may output first multiplication result data MUL1 with M×N bits generated by the first multiplying calculation of the first multiplier 1110. The second multiplier 1120 may perform a second multiplying calculation of the first input data DA11 with N bits and the second input data DA21 with M bits. The second multiplier 1120 may output second multiplication result data MUL2 with M×N bits generated by the second multiplying calculation of the second multiplier 1120. The first multiplication result data MUL1 with M×N bits that are output from the first multiplier 1110 and the second multiplication result data MUL2 with M×N bits that are output from the first multiplier 1120 may be transmitted to the adder 1210 of the adding circuit 1200.

The adder 1210 may perform an adding calculation of the first multiplication result data MUL1 with M×N bits and the second multiplication result data MUL2 with M×N bits. The adder 1210 may output addition result data ADD1 generated by the adding calculation of the adder 1210. The addition result data ADD1 may be generated to have the same number of bits (i.e., M×N bits) as each of the first multiplication result data MUL1 and the second multiplication result data MUL2.

FIG. 32 illustrates a configuration of the adder 1210 of the adding circuit 1200 included the MAC circuit 1000 illustrated in FIG. 31. Referring to FIG. 32, the adder 1210 may include an AND gate 1211 and a plurality of full adders (e.g., first to fifteenth full adders 1212(1)˜1212(15)). Hereinafter, it may be assumed that the adder 1210 receives first input data A[15:0] with 16 bits and second input data B[15:0] with 16 bits. The first input data A[15:0] may correspond to the first multiplication result data MUL1 that is output from the first multiplier 1110 described with reference to FIG. 31, and the second input data B[15:0] may correspond to the second multiplication result data MUL2 that is output from the second multiplier 1120 described with reference to FIG. 31.

The AND gate 1211 may receive a least significant bit (LSB) value (i.e., a first bit value) A[0] of the first input data A[15:0] and an LSB value (i.e., a first bit value) B[0] of the second input data B[15:0]. The AND gate 1211 may perform a logical AND operation for the first bit value A[0] of the first input data A[15:0] and the first bit value B[0] of the second input data B[15:0]. The AND gate 1211 may output a first carry bit value C[0] as a result of the logical AND operation of the AND gate 1211, and the first carry bit value C[0] may be input to the first full adder 1212(1).

The number of the first to fifteenth full adders 1212(1)-1212(15) may be one less than the number of bits included in each of the first input data A[15:0] and the second input data B[15:0]. In the present embodiment, because the number of bits included in each of the first input data A[15:0] and the second input data B[15:0] is sixteen, fifteen full adders (i.e., the first to fifteenth full adders 1212(1)-1212(15)) may be disposed in the adder 1210. The first to fifteenth full adders 1212(1)-1212(15)) may be coupled in series such that a carry bit value that is output from a certain full adder of the first to fourteenth full adders 1212(1)-1212(14)) is input to a full adder next to the certain full adder. For example, a second carry bit value C[1] that is output from the first full adder 1212(1) may be input to the second full adder 1212(2). Similarly, a fifteenth carry bit value C[14] that is output from the fourteenth full adder 1212(14) may be input to the fifteenth full adder 1212(15).

Each of the first to fifteenth full adders 1212(1)˜1212(15) may perform an adding calculation of one of bit values of the first input data A[15:1], one of bit values of the second input data B[15:1], and a previous carry bit value C that is output from a previous full adder to output an added bit value S and a carry bit value C. The first to fifteenth full adders 1212(1)˜1212(15) may receive the second to sixteenth bit values A[15:1] of the first input data A as first input values, respectively. Similarly, the first to fifteenth full adders 1212(1)˜1212(15) may receive the second to sixteenth bit values B[15:1] of the second input data B as second input values, respectively.

Added bit values S[14:0] that is output from respective ones of the first to fifteenth full adders 1212(1)˜1212(15) may constitute bit values that remain after excepting a most significant bit (MSB) value (i.e., a sixteenth bit value) S[15] of output data S[15:0] of the adder 1210 from the output data S[15:0] of the adder 1210. A carry bit value C that is output from each of the first to fourteenth full adders 1212(1)-1212(14) may be input to a next full adder, as described previously. In contrast, a carry bit value C that is output from the fifteenth full adder 1212(15) may correspond to an MSB value of the output data S[15:0] of the adder 1210. The output data S[15:0] of the adder 1210 may correspond to the addition result data ADD1 that is output from the adder 1210 described with reference to FIG. 31.

More specifically, the first full adder 1212(1) may perform an adding calculation of the second bit value A[1] of the first input data A[15:0], the second bit value B[1] of the second input data B[15:0], and the first carry bit value c[0] that is output from the AND gate 1211. The first full adder 1212(1) may output the second carry bit value C[1] and the first bit value S[0] of the output data S[15:0] as a result of the adding calculation of the first full adder 1212(1). The second full adder 1212(2) may perform an adding calculation of the third bit value A[2] of the first input data A[15:0], the third bit value B[2] of the second input data B[15:0], and the second carry bit value C[1] that is output from the first full adder 1212(1). The second full adder 1212(2) may output a third carry bit value C[2] and a second bit value S[1] of the output data S[15:0] as a result of the adding calculation of the second full adder 1212(2).

The third to fifteenth full adders 1212(3)˜1212(15) may be sequentially perform the adding calculation described above. Accordingly, the fifteenth full adder 1212(15) may perform an adding calculation of the sixteenth bit value A[15] of the first input data A[15:0], the sixteenth bit value B[15] of the second input data B[15:0], and a fifteenth carry bit value C[14] that is output from the fourteenth full adder 1212(14). The fifteenth full adder 1212(15) may output an added value and a sixteenth carry bit value as a result of the adding calculation of the fifteenth full adder 1212(15). The added value that is output from the fifteenth full adder 1212(15) may correspond to the fifteenth bit value S[14] of the output data S[15:0], and the carry bit value that is output from the fifteenth full adder 1212(15) may correspond to the sixteenth bit value S[15] of the output data S[15:0].

As described above, the adder 1210 according to the present embodiment may receive the first input data A[15:0] with 16 bits and the second input data B[15:0] with 16 bits to output the output data S[15:0] with 16 bits. Thus, the number of bits included in the output data S[15:0] that is output from the adder 1210 may be equal to the number of bits included in each of the first input data A[15:0] and the second input data B[15:0] which are input to the adder 1210.

FIG. 33 is a block diagram illustrating a MAC circuit 2000 according to another embodiment of the present disclosure. Referring to FIG. 33, the MAC circuit 2000 may include a multiplying circuit 2100 and an adding circuit 2200. The multiplying circuit 2100 may include a plurality of multipliers MULs. Each of the plurality of multipliers MULs may receive first input data and second input data with the same number of bits. Hereinafter, it may be assumed that each of the plurality of multipliers MULs receives the first input data with 16 bits and the second input data with 16 bits. In such a case, each of the plurality of multipliers MULs may perform a multiplying calculation for the first input data and the second input data to output multiplication result data with 32 bits. In an embodiment, when the MAC circuit 2000 performs a MAC arithmetic operation for the first input data with 1024 bits and the second input data with 1024 bits, the multiplying circuit 2100 may be designed to have 64 multipliers MULs, each of which performs a multiplying calculation for the first input data with 16 bits and the second input data with 16 bits.

The adding circuit 2200 may be designed to have a plurality of stages (e.g., “K”-number of stages). Each of the “K”-number of stages may include at least one adder ADD. A highest order stage (i.e., a first stage) of the plurality of stages included in the adding circuit 2200 may include a plurality of adders ADD_1 s which are disposed in parallel, and the number of the plurality of adders ADD_1 s in the first stage may be half of the number of the multipliers MULs disposed in the multiplying circuit 2100. A second stage of the adding circuit 2200 may include a plurality of adders ADD_2 s which are disposed in parallel, and the number of the plurality of adders ADD_2 s in the second stage may be half of the number of the adders ADD_1 s disposed in the first stage of the adding circuit 2200. That is, when a plurality of adders are disposed in parallel in a low-order stage, the number of the adders ADDs in the low-order stage may be half of the number of adders ADDs in a high-order stage immediately adjacent to the low-order stage. Thus, the last stage (i.e., a K^(th) stage) of the adding circuit 2200 may be designed to have one adder ADD_K.

Each of the adders ADD_1 s in the first stage of the adding circuit 2200 may perform an adding calculation for output data of two of the multipliers MULs included in the multiplying circuit 2100 and may output addition result data generated by the adding calculation. Each of the adders ADD_2 s in the second stage of the adding circuit 2200 may perform an adding calculation for output data of two of the adders ADD_1 s in the first stage of the adding circuit 2200 and may output addition result data generated by the adding calculation. The adder ADD_K in the K^(th) stage of the adding circuit 2200 may perform an adding calculation for output data of the two adders ADD_(K−1)s in the (K−1)^(th) stage of the adding circuit 2200 and may output addition result data generated by the adding calculation of the adder ADD_K.

Each of the adders ADD_1-ADD_K constituting the adding circuit 2200 may generate the output data with the same number of bits as any one of two groups of input data thereof. Each of the adders ADD_1-ADD_K constituting the adding circuit 2200 may have the same configuration as the adder 1210 described with reference to FIG. 32. Thus, detailed descriptions of the adders ADD_1-ADD_K will be omitted hereinafter to avoid duplicate explanation.

As described above, it may be assumed that the MAC circuit 2000 performs a MAC arithmetic operation for first input data with 1024 bits and second input data with 1024 bits and each of the multipliers MULs in the multiplying circuit 2100 performs a multiplying calculation for first input data with 16 bits and second input data with 16 bits. In such a case, each of the multipliers MULs in the multiplying circuit 2100 may generate output data with 32 bits. That is, each of the adders ADD_1 s in the first stage of the adding circuit 2200 may receive first input data with 32 bits and second input data with 32 bits. Each of the adders ADD_1 s in the first stage of the adding circuit 2200 may perform an adding calculation for the first input data and the second input data to generate 32-bit output data. Because each of the adders ADD_1 s in the first stage outputs 32-bit output data, each of the adders ADD_2 s in the second stage may receive first input data with 32 bits and second input data with 32 bits. Each of the adders ADD_2 s in the second stage of the adding circuit 2200 may also perform an adding calculation for the first input data and the second input data to generate 32-bit output data. In the same way, the adder ADD_K in the K^(th) stage corresponding to the last stage of the adding circuit 2200 may also generate 32-bit output data.

In general, input data used in a PIM system performing arithmetic operations of a neural network may be categorized as either fixed-point type data or floating-point type data. When the input data are the fixed-point type data, output data of a general MAC circuit may be generated through a plurality of stages in an adder tree and the number of bits included in the output data of the general MAC circuit may increase to be greater than the number of bits included in input data of the MAC circuit. Thus, in such a case, it may be necessary to reduce the number of bits included in the output data using a quantization process such that the input data and the output data have the same number of bits. In addition, even when the input data are the floating-point type data, it may be necessary to convert the floating-point type data into the fixed-point type data using a quantization process. Even in such a case, it may be necessary to reduce the number of bits included in the output data of the MAC circuit. However, according to the present embodiment described above, the number of bits included in the output data of the MAC circuit 2000 may remain constant without increasing. Thus, when a subsequent arithmetic operation is performed by the MAC circuit 2000, the MAC circuit 2000 may exhibit a high efficiency in terms of a hardware area and power consumption.

A limited number of possible embodiments for the present teachings have been presented above for illustrative purposes. Those of ordinary skill in the art will appreciate that various modifications, additions, and substitutions are possible. While this patent document contains many specifics, these should not be construed as limitations on the scope of the present teachings or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 

What is claimed is:
 1. A multiplying-and-accumulating (MAC) circuit comprising: a multiplying circuit including a first multiplier and a second multiplier, wherein each of the first multiplier and the second multiplier performs a multiplying calculation for first input data with N bits and second input data with M bits to output multiplication result data with (N+M) bits (where, “N” and “M” are natural numbers which are equal to or greater than one); and an adding circuit including an adder which performs an adding calculation for the multiplication result data of the first multiplier and the multiplication result data of the second multiplier to output addition result data with (N+M) bits.
 2. The MAC circuit of claim 1, wherein “N” is equal to “M”.
 3. The MAC circuit of claim 1, wherein the adder includes: an AND operator configured to perform a logical AND operation for a least significant bit (LSB) value of the multiplication result data of the first multiplier and an LSB value of the multiplication result data of the second multiplier to output a first carry bit value; and a plurality of full adders sequentially coupled in series to an output terminal of the AND operator, wherein a carry bit value that is output from an (I−1)^(th) full adder of the plurality of full adders is input to an I^(th) full adder of the plurality of full adders (where, “I” is a natural number which is equal to or greater than two).
 4. The MAC circuit of claim 3, wherein the number of the plurality of full adders is one less than the number of bits included in the multiplication result data.
 5. The MAC circuit of claim 3, wherein each of the plurality of full adders is configured to receive a first input bit value, a second input bit value, and a previous carry bit value to output an added bit value and a carry bit value.
 6. The MAC circuit of claim 5, wherein each of the plurality of full adders is configured to receive one of second to most significant bit (MSB) values included in the multiplication result data of the first multiplier and one of second to MSB values included in the multiplication result data of the second multiplier.
 7. The MAC circuit of claim 6, wherein bit values remaining after excepting an MSB value of the addition result data of the adder from the addition result data of the adder correspond to the added bit values that are output from respective ones of the plurality of full adders.
 8. The MAC circuit of claim 7, wherein an MSB value of the addition result data that is output from the adder corresponds to a carry bit value that is output from a last full adder of the plurality of full adders.
 9. A multiplying-and-accumulating (MAC) circuit comprising: a multiplying circuit including a plurality of multipliers, wherein each of the plurality of multipliers performs a multiplying calculation for first input data with N bits and second input data with M bits to output multiplication result data with (N+M) bits (where, “N” and “M” are natural numbers which are equal to or greater than one); and an adding circuit configured to receive output data of the multiplying circuit, wherein the adding circuit has a tree structure including a plurality of stages, each of which has one or more adders, and wherein each of the adders is configured to receive first data and second data to generate output data with the same number of bits as the first data or the second data.
 10. The MAC circuit of claim 9, wherein each of the adders in a first stage corresponding to a highest-order stage of the plurality of stages is configured to receive multiplication result data that is output from two of the plurality of multipliers; and wherein each of the adders in a J^(th) stage of the plurality of stages is configured to receive addition result data that is output from two of the adders in a (J−1)^(th) stage of the plurality of stages (where, “J” is a natural number which is equal to or greater than two).
 11. The MAC circuit of claim 9, wherein “N” is equal to “M”.
 12. The MAC circuit of claim 9, wherein each of the adders includes: an AND operator configured to perform a logical AND operation for a least significant bit (LSB) value of the first data and an LSB value of the second data to output a first carry bit value; and a plurality of full adders sequentially coupled in series to an output terminal of the AND operator, wherein a carry bit value that is output from an (I−1)^(th) full adder of the plurality of full adders is input to an I^(th) full adder of the plurality of full adders (where, “I” is a natural number which is equal to or greater than two).
 13. The MAC circuit of claim 12, wherein the number of the plurality of full adders is one less than the number of bits included in the first data or the second data.
 14. The MAC circuit of claim 12, wherein each of the plurality of full adders is configured to receive a first input bit value, a second input bit value, and a previous carry bit value to output an added bit value and a carry bit value.
 15. The MAC circuit of claim 14, wherein each of the plurality of full adders is configured to receive one of second to most significant bit (MSB) values included in the first data and one of second to MSB values included in the second data.
 16. The MAC circuit of claim 15, wherein bit values remaining after excepting an MSB value in addition result data of the adder from the addition result data of the adder correspond to the added bit values that are output from respective ones of the plurality of full adders constituting the adder.
 17. The MAC circuit of claim 16, wherein an MSB value of the addition result data that is output from the adder corresponds to a carry bit value that is output from a last full adder of the plurality of full adders. 